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HUMAN FOODS AND THEIR 
NUTRITIVE VALUE 



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THE M ACM ILL AN COMPANY 

NEW YORK • BOSTON • CHICAGO 
ATLANTA • SAN FRANCISCO 

MACMILLAN & CO., Limited 

LONDON • BOMBAY • CALCUTTA 
MELBOURNE 

THE MACMILLAN CO. OF CANADA, Ltd. 

TORONTO 



HUMAN FOODS 

AND THEIR NUTRITIVE VALUE 



BY 

HARRY SNYDER, B.S. 

PROFESSOR OF AGRICULTURAL CHEMISTRY, UNIVERSITY OF 

MINNESOTA, AND CHEMIST OF THE MINNESOTA 

EXPERIMENT STATION 



THE MACMILLAN COMPANY 

All rights reserved 



^^ 



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LIBRARY of CONGRESS 
Two Copi"-; Per.flived 

NOV 30 1908 

OepyriKMi t-Mtry 
CLASS A, ' XXc, No, 



Copyright, 1908, 
By the MACMILLAN COMPANY. 



Set up and electrotyped. Published November, igo8. 



NorfajooU i^ress 

J. S. Cushing- Co. — Berwick & Smith Co. 

Norwood, Mass., U.S.A. 



PREFACE 

Since 1897 instruction has been given at the Uni- 
versity of Minnesota, College of Agriculture, on human 
foods and their nutritive value. With the development 
of the work, need has been felt for a text-book present- 
ing in concise form the composition and physical prop- 
erties of foods, and discussing some of the main factors 
which affect their nutritive value. To meet the need, 
this book has been prepared, primarily for the author's 
classroom. It aims to present some of the principles 
of human nutrition along with a study of the more com- 
mon articles of food. It is believed that a better under- 
standing of the subject of nutrition will suggest ways 
in which foods may be selected and utilized more intel- 
ligently, resulting not only in pecuniary saving, but also 
in greater efficiency of physical and mental effort. 

Prominence is given in this work to those foods, as 
flour, bread, cereals, vegetables, meats, milk, dairy 
products, and fruits, that are most extensively used in 
the dietary, and to some of the physical, chemical, and 
bacteriological changes affecting digestibility and nutri- 
tive value which take place during their preparation 
for the table. Dietary studies, comparative cost and 
value of foods, rational feeding of men, and experiments 



VI PREFACE 

and laboratory practice form features of the work. Some 
closely related topics, largely of a sanitary nature, as 
the effect upon food of household sanitation and storage, 
are also briefly discussed. References are given in 
case more extended information is desired on some of 
the subjects treated. While this book was prepared 
mainly for students who have taken a course in general 
chemistry, it has been the intention to present the topics 
in such a way as to be understood by the layman also. 

This work completes a series of text-books under- 
taken by the author over ten years ago, dealing with 
agricultural and industrial subjects : " Chemistry of 
Plant and Animal Life," "Dairy Chemistry," ** Soils 
and Fertilizers," and " Human Foods and their Nutritive 
Value." It has been the aim in preparing these books 
to avoid as far as possible repetition, but at the same 
time to make each work sufficiently complete to permit 
its use as a text independent of the series. 

One of the greatest uses that science can serve is in 

its application to the household and the everyday affairs 

of life. Too little attention is generally bestowed upon 

the study of foods in schools and colleges, and the 

author sincerely hopes the time will soon come when 

more prominence will be given to this subject, which 

is the oldest, most important, most neglected, and least 

understood of any that have a direct bearing upon the 

welfare of man. 

HARRY SNYDER. 



CONTENTS 



CHAPTER I 

PAGE 

General Composition of Foods i 

Water ; Dry Matter ; Variations in Weight of Foods ; 
Ash ; Function of Ash in Plant Life ; Organic Matter ; 
Products of Combustion of Organic Matter ; Classification 
of Organic Compounds; Non-nitrogenous Compounds;- 
Carbohydrates ; Cellulose ; Amount of Cellulose in Foods ; 
Crude Fiber ; Starch ; Microscopic Structure of Starch ; 
Dextrin ; Food Value of Starch ; Sugar ; Pectose Sub- 
stances ; Nitrogen-free-extract ; Fats ; Fuel Value of Fats ; 
Iodine Number of Fats ; Glycerol Content of Fats ; Ether 
Extract and Crude Fat ; Organic Acids ; Dietetic Value 
of Organic Acids; Essential Oils; Mixed Compounds: 
Nutritive Value of Non-nitrogenous Compounds ; Nitrog- 
enous Compounds ; General Composition ; Protein ; Sub- 
divisions of Proteins ; Crude Protein ; Food Value of 
Protein ; Albuminoids ; Amids and Amines ; Alkaloids ; 
General Relationship of the Nitrogenous Compounds. 

CHAPTER II 

Changes in Composition of Foods during Cooking and 

Preparation 27 

Raw and Cooked Foods compared as to Composition ; 
Chemical Changes during Cooking; General Changes 
affecting Cellulose, Starch, Sugar, Pectin Bodies, Fats, 



Vili CONTENTS 



Proteids ; Effect of Chemical Changes on Digestibility ; 
Physical Changes during Cooking; Action of Heat on 
Animal and Plant Tissues ; Amount of Heat required for 
Cooking ; Bacteriological Changes ; Insoluble Ferments ; 
Soluble Ferments ; Bacterial Action Necessary in Prepa- 
ration of Some Foods; Injurious Bacterial Action; Gen- 
eral Relationship of Chemical, Physical, and Bacteriological 
Changes ; Esthetic Value of Foods ; Color of Foods, 
Natural and Artificial Colors; Conditions under which 
Use of Chemicals in Preparation of Foods is Justifiable. 



CHAPTER III 

Vegetable Foods 37 

General Composition ; Potatoes ; Chemical and Me- 
chanical Composition ; Uses of Potatoes in Dietary ; Sweet 
Potatoes ; Carrots ; Parsnips, Cabbage ; Cauliflower ; 
Beets ; Cucumbers ; Lettuce ; Onions ; Spinach ; Aspara- 
gus ; Melons; Tomatoes; Sweet Corn; Eggplant; 
Squash ; Celery ; Dietetic Value of Vegetables ; Nutrient 
Content of Vegetables ; Sanitary Condition of Vegetables ; 
Miscellaneous Compounds in Vegetables ; Canned Vege- 
tables ; Edible Portion and Refuse of Vegetables. 



CHAPTER IV 

Fruits, Flavors, and Extracts 48 

General Composition ; Food Value ; Apples ; Oranges ; 
Lemons; Grape Fruit; Strawberries; Grapes; Peaches; 
Plums ; Olives ; Figs ; Dried Fruits ; Uses of Fruit in 
the Dietary ; Canning and Preservation of Fruits ; Adul- 
terated Canned Fruits ; Fruit Flavors and Extracts ; Syn- 
thetic Preparation of Flavors. 



CONTENTS IX 

CHAPTER V 

PAGE 

Sugars, Molasses, Syrup, Honey, and Confections . 58 
Composition of Sugars ; Beet Sugar ; Cane Sugar ; 
Manufacture of Sugar; Sulphur Dioxid and Indigo, Uses 
of, in Sugar Manufacture ; Commercial Grades of Sugar ; 
Sugar in the Dietary ; Maple Sugar ; Adulteration of 
Sugar ; Dextrose Sugars ; Inversion of Sugars ; Molasses ; 
Syrups ; Adulteration of Molasses ; Sorghum Syrup ; 
Maple Syrup ; Analysis of Sugar ; Adulteration of Syrups ; 
Honey ; Confections ; Coloring Matter in Candies ; Coal 
Tar Dyes ; Saccharine. 

CHAPTER VI 

Legumes and Nuts 71 

General Composition of Legumes ; Beans ; Digesti- 
bility of Beans ; Use of Beans in the Dietary ; String 
Beans ; Peas ; Canned Peas ; Peanuts ; General Compo- 
sition of Nuts ; Chestnuts ; The Hickory Nut ; Almonds ; 
Pistachio ; Cocoanuts ; Uses of Nuts in the Dietary. 

CHAPTER VII 

Milk and Dairy Products 80 

Importance in the Dietary ; General Composition ; Di- 
gestibility ; Sanitary Condition of Milk ; Certified Milk ; 
Pasteurized Milk ; Tyrotoxicon ; Color of Milk ; Souring 
of Milk ; Use of Preservatives in Milk ; Condensed Milk ; 
Skim Milk; Cream; Buttermilk; Goat's Milk ; Koumiss; 
Prepared Milks; Human Milk; Adulteration of Milk; 
Composition of Butter; Digestibihty of Butter; Adul- 
teration of Butter ; General Composition of Cheese ; 
Digestibility ; Use in the Dietary ; Cottage Cheese ; Differ- 



CONTENTS 



ent Kinds of Cheese ; Adulteration of Cheese ; Dairy 
Products in the Dietary. 



CHAPTER VIII 

Meats and Animal Food Products 98 

General Composition ; Mineral Matter ; Fat ; Protein ; 
Non-nitrogenous Compounds ; Why Meats vary in Com- 
position ; Amides ; Albuminoids ; Taste and Flavor of 
Meats ; Alkaloidal Bodies in Meats ; Ripening of Meats 
in Cold Storage; Beef; Veal; Mutton; Pork; Lard; 
Texture and Toughness of Meat ; Influence of Cooking 
upon the Composition of Meats ; Beef Extracts ; Miscel- 
laneous Meat Products ; Pickled Meats ; Saltpeter in 
Meats ; Smoked Meats ; Poultry ; Fish ; Oysters, Fatten- 
ing of; Shell Fish ; Eggs, General Composition ; Digesti- 
bility of Eggs; Use of Eggs in the Dietary; Canned 
Meats, General Composition. 



CHAPTER IX 

Cereals . . . . . . . . . .121 

Preparation and Cost of Cereals : Various Grains used 
in making Cereal Products; Cleanliness of; Corn Prepa- 
rations ; Corn Flour ; Use of Corn in Dietary ; Corn Bread ; 
Oat Preparations ; Cooking of Oatmeal ; Wheat Prepara- 
tions ; Flour Middlings ; Breakfast Foods ; Digestibility 
of Wheat Preparations ; Barley Preparations ; Rice Prepa- 
rations ; Predigested Foods ; The Value of Cereals in the 
Dietary ; Phosphate Content of Cereals ; Phosphorus Re- 
quirements of a Ration ; Mechanical Action of Cereals 
upon Digestion ; Cost and Nutritive Value of Cereals. 



CONTENTS Xi 

CHAPTER X 

PAGE 

Wheat Flour 133 

Use for Bread Making ; Winter and Spring Wiieat 
Flours ; Composition of Wheat and Flour ; Roller Process 
of Flour Milling ; Grades of Flour ; Types of Flour ; Com- 
position of Flour ; Graham and Entire Wheat Flours ; 
Composition of Wheat Offals ; Aging and Curing of Flour ; 
Macaroni Flour ; Color ; Granulation ; Capacity of Flour 
to absorb Water ; Physical Properties of Gluten ; Gluten 
as a Factor in Bread Making ; Unsoundness ; Comparative 
Baking Tests ; Bleaching ; Adulteration of Flour ; Nutri- 
tive Value of Flour. 

CHAPTER XI 

Bread and Bread Making 158 

Leavened and Unleavened Bread; Changes during 
Bread Making ; Loss of Dry Matter during Bread Making : 
Action of Yeast ; Compressed Yeast ; Dry Yeast ; Pro- 
duction of Carbon Dioxid Gas and Alcohol ; Production 
of Soluble Carbohydrates ; Production of Acids in Bread 
Making ; Volatile Compounds produced during Bread 
Making; Behavior of Wheat Proteids in Bread Making; 
Production of Volatile Nitrogenous Compounds ; Oxida- 
tion of Fat ; Influence of the Addition of Wheat Starch 
and Gluten to Flour; Composition of Bread; Use of 
Skim Milk and Lard in Bread Making; Influence of 
Warm and Cold Flours in Bread Making ; Variations in 
the Process of Bread Making; Digestibility of Bread; 
Use of Graham and Entire Wheat in the Dietary ; Min- 
eral Content of White Bread ; Comparative Digestibility 
of New and Old Bread ; Different Kinds of Bread ; Toast. 



Xll CONTENTS 



CHAPTER XII 

PAGE 

Baking Powders i86 

General Composition ; Cream of Tartar Powders ; Resi- 
due from Cream of Tartar Baking Powders ; Tartaric 
Acid Powders ; Phosphate Baking Powders ; Mineral and 
Organic Phosphates ; Phosphate Residue ; Alum Baking 
Powders ; Residue from Alum Baking Powders ; Objec- 
tions urged against Alum Powders ; Action of Baking 
Powders and Yeast Compared ; Keeping Qualities of 
Baking Powders ; Inspection of Baking Powders ; Fillers; 
Home-made Baking Powders. 

CHAPTER XIII 

Vinegar, Spices, and Condiments 193 

Vinegar ; Chemical Changes during Manufacture of 
Vinegar ; Ferment Action ; Materials used in Preparation 
of Vinegars ; Characteristics of a Good Vinegar ; Vinegar 
Solids ; Acidity of Vinegar ; Different Kinds of Vinegars ; 
Standards of Purity ; Adulteration of Vinegar ; Character- 
istics of Spices ; Pepper ; Cayenne ; Mustard ; Ginger ; 
Cinnamon and Cassia ; Cloves; Allspice; Nutmeg; Adul- 
teration of Spices and Condiments; Essential Oils of; 
Uses of Condiments in Preparation of Foods ; Action of 
Condiments upon Digestion ; Condiments and Natural 
Flavors. 

CHAPTER XIV 

Tea, Coffee, Chocolate, and Cocoa .... 203 

Tea ; Sources of Tea Supply ; Composition of Tea ; 
Black Tea and Green Tea ; Judging Teas ; Adulteration 
of Tea ; Food Value and Physiological Properties of Tea ; 



CONTENTS Xlll 



PAGE 



Composition of Coffee ; Adulteration of Coffee ; Chicory 
in Coffee ; Glazing of Coffee ; Cereal Coffee Substitutes ; 
Cocoa and Chocolate Preparations ; Composition of Cocoa ; 
Chocolate ; Cocoa Nibs ; Plain Chocolate ; Sweet Choco- 
late ; Cocoa Butter ; Nutritive Value of Cocoa ; Adultera- 
tion of Chocolate and Cocoa; Comparative Composition 
of Beverages. 

CHAPTER XV 

The Digestibility of Foods 214 

Digestibility, how Determined ; Completeness and Ease 
of Digestion Process ; Example of Digestion Experiment ; 
Available Nutrients ; Available Energy ; Caloric Value of 
Foods ; Normal Digestion and Health ; DigestibiHty of 
Animal Foods ; Digestibility of Vegetable Foods ; Factors 
influencing Digestion ; Combination of Foods ; Amount 
of Food ; Method of Preparation of Food ; Mechanical 
Condition of Foods ; Mastication ; Palatability of Foods ; 
Physiological Properties of Foods ; Individuality ; Psy- 
chological Factors. 

CHAPTER XVI 
Comparative Cost and Value of Foods . . .231 

Cost and Nutrient Content of Foods ; How to compare 
Two Foods as to Nutritive Value ; Cheap Foods ; Expen- 
sive Foods ; Nutrients Procurable for a Given Sum ; Ex- 
amples ; Comparing Nutritive Value of Common Foods 
at Different Prices ; Cost and Value of Nutrients. 

CHAPTER XVII 

Dietary Studies 244 

Object of Dietary Studies ; Wide and Narrow Rations; 
Dietary Standards ; Number of Meals per Day ; Mixed 



XIV CONTENTS 

PAGE 

Dietary Desirable ; Animal and Vegetable Foods ; 
Economy of Production ; Food Habits ; Underfed Fami- 
lies ; Cheap and Expensive Foods ; Food Notions ; 
Dietary of Two Families Compared ; f^ood in its Relation 
to Mental and Physical Vigor ; Dietary Studies in Public 
Institutions. 

CHAPTER XVni 

Rational Feeding of Man .261 

Object ; Human and Animal Feeding Compared ; Stand- 
ard Rations ; Why Tentative Dietary Standards ; Amounts 
of Food Consumed ; Average Composition of Foods ; 
Variations in Composition of Foods ; Example of a Ra- 
tion ; Calculations of Balanced Rations ; Requisites of a 
Balanced Ration ; Examples ; Calculations of Rations for 
Men at Ditferent Kinds of Labor. 

CHAPTER XIX 
Water 268 

Importance; Impurities in Water; Mineral Impurities; 
Organic Impurities ; Interpretation of a Water Analysis ; 
Natural Purification of Water ; Water in Relation to 
Health; Improvement of Waters ; Boiling of Water ; Fil- 
tration ; Purification of Water by Addition of Chemicals ; 
Ice; Rain Waters; Waters of High and Low Purity; 
Chemical Changes which Organic Matter of Water Un- 
dergoes ; Bacterial Content of Water ; Mineral Waters ; 
Materials for Softening Water ; Uses of ; Economic Value 
of a Pure Water Supply. 

CHAPTER XX 

Food as affected by Household Sanitation and 

Storage 284 

Injurious Compounds in Foods; Nutrient Content and 



CONTENTS XV 



Sanitary Condition of Food ; Sources of Contamination 
of Food ; Unclean Ways of Handling Food ; Sanitary In- 
spection of Food ; Infection from Impure Air ; Storage 
of Food in Cellars ; Respiration of Vegetable Cells ; Sun- 
light, Pure Water, and Pure Air as Disinfectants ; Foods 
contaminated from Leaky Plumbing ; Utensils for Storage 
of Food ; Contamination from Unclean Dishcloths ; Re- 
frigeration ; Chemical Changes that take Place in the 
Refrigerator; Soil; Disposal of Kitchen Refuse;' Germ 
Diseases spread by Unsanitary Conditions around Dwell- 
ings due to Contamination of Food ; General Considera- 
tions ; Relation of Food to Health. 

CHAPTER XXI 

Laboratory Practice 299 

Object of Laboratory Practice; Laboratory Note-book 
and Suggestions for Laboratory Practice ; List of Appara- 
tus Used; Photograph of Apparatus Used; Directions 
for Weighing ; Directions for Measuring ; Use of Micro- 
scope ; Water in Flour; Water in. Butter; Ash in Flour; 
Nitric Acid Test for Nitrogenous Organic Matter ; Acidity 
of Lemons; Influence of Heat on Potato Starch Grains; 
Influence of Yeast on Starch Grains ; Mechanical Compo- 
sition of Potatoes ; Pectose from Apples ; Lemon Extract ; 
Vanilla Extract ; Testing Olive Oil for Cotton Seed Oil ; 
Testing for Coal Tar Dyes ; Determining the Per Cent of 
Skin in Beans ; Extraction of Fat from Peanuts ; Micro- 
scopic Examination of Milk ; Formaldehyde in Cream or 
Milk ; Gelatine in Cream or Milk ; Testing for Oleomarga- 
rine ; Testing for Watering or Skimming of Milk ; Boric 
Acid in Meat ; Microscopic Examination of Cereal Starch 
Grains ; Identification of Commercial Cereals ; Granula- 
tion and Color of Flour ; Capacity of Flour to absorb 



XVI CONTENTS 



Water ; Acidity of Flour ; Moist and Dry Gluten ; Gliadin 
from Flour; Bread-making Test; Microscopic Examina- 
tion of Yeast; Testing Baking Powders for Alum ; Test- 
ing Baking Powders for Phosphoric Acid ; Testing Baking 
Powders for Ammonia ; Vinegar Solids ; Specific Gravity 
of Vinegar ; Acidity of Vinegar ; Deportment of Vinegar 
with Reagents ; Testing Mustard for Turmeric ; Examina- 
tion of Tea Leaves ; Action of Iron Compounds upon 
Tannic Acid ; Identification of Coffee Berries ; Detecting 
Chicory in Coffee ; Comparative Amounts of Soap Neces- 
sary with Hard and Soft Water ; Solvent Action of Water 
on Lead ; Suspended Matter in Water ; Organic Matter 
in Water ; Deposition of Lime by Boiling Water ; Quali- 
tative Tests for Minerals in Water; Testing for Nitrites 
in Water. 

Review Questions 323 

References 350 

Index 357 



HUMAN FOODS AND THEIR 
NUTRITIVE VALUE 



HUMAN FOODS AND THEIR 
NUTRITIVE VAEUE 

CHAPTER I 

GENERAL COMPOSITION OF FOODS 

1. Water. — All foods contain water. Vegetables in 
their natural condition contain large amounts, often 95 
per cent, while in meats there is from 40 to 60 per cent 
or more. Prepared cereal products, as flour, corn meal, 
and oatmeal, which are apparently dry*, have from 7 to 
14 per cent. In general the amount of water in a food 
varies with the mechanical structure and the conditions 
under which it has been prepared, and is an important 
factor in estimating the value, as the nutrients are often 
greatly decreased because of large amounts of water. 
The water in substances as flour and meal is mechani- 
cally held in combination with the fine particles and 
varies with the moisture content, or hydroscopicity, of 
the air. Oftentimes foods gain or lose water to such 
an extent as to affect their weight; for example, one 
hundred pounds of flour containing 12 per cent of 
water may be reduced in weight three pounds or more 
when stored in a dry place, or there may be an increase 



2 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

in weight from being stored in a damp place. In 
tables of analyses the results, unless otherwise stated, 
are usually given on the basis of the original material, 
or the dry substance. Potatoes, for example, contain 
2-| per cent of crude protein on the basis of 75 per cent 
of water; or on a dry matter basis, that is, when the 
water is entirely eliminated, there is 10 per cent of 
protein. 

The water of foods is determined by drying the 
weighed material in a water or air oven at a tempera- 
ture of about 100° C, until all of the moisture has been 
expelled in the form of steam, leaving the dry matter or 
material free from water.^ The determination of dry 
matter, while theoretically a simple process, is attended 
with many difficulties. Substances which contain much 
fat may undergo oxidation during drying; volatile com- 
pounds, as essential oils, are expelled along with the 
moisture; and other changes may occur affecting the 
accuracy of the work. The last traces of moisture are 
removed with difficulty from a substance, being me- 
chanically retained by the particles with great tenacity. 
When very accurate dry matter determinations are de- 
sired, the substance is dried in a vacuum oven, or in a 
desiccator over sulphuric acid, or in an atmosphere of 
some non-oxidizing gas, as hydrogen. 

2. Dry Matter. — The dry matter of a food is a me- 
chanical mixture of the various compounds, as starch, 
sugar, fat, protein, cellulose, and mineral matter, and is 



GENERAL COMPOSITION OF FOODS 




Fig. I. — Apparatus used for the Determination of Dry Matter 
AND Ash in Foods. 

I, desiccator; 2, muffle furnace for combustion of foods and obtaining ash; 
3, water oven for drying food materials. 

obtained by drying the material. Succulent vegetable 
foods with 95 per cent of water contain only 5 per cent 



4 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

of dry matter, while in flour with 12 per cent of water 
there is 88 per cent, and in sugar 99 per cent. The 
dry matter is obtained by subtracting the per cent of 
water from 100, and in foods it varies from 5 per cent 
and less in some vegetables to 99 per cent in sugar. 

3. Ash. — The ash, or mineral matter, is that portion 
obtained by burning or igniting the dry matter at the 
lowest temperature necessary for complete combustion. 
The ash in vegetable foods ranges from 2 to 5 per cent 
and, together with the nitrogen, represents what was 
taken from the soil during growth. In animal bodies, 
the ash is present mainly in the bones, but there is also 
an appreciable amount, one per cent or more, in all the 
tissues. Ash is exceedingly variable in composition, 
being composed of the various salts of potassium, so- 
dium, calcium, magnesium, and iron, as sulphates, phos- 
phates, chlorides, and silicates of these elements. There 
are also other elements in small amounts. In the plant 
economy these elements take an essential part and are 
requisite for the formation of plant tissue and the pro- 
duction in the leaves of the organic compounds which 
later are stored up in the seeds. Some of the elements 
appear to be more necessary than others, and whenever 
withheld plant growth is restricted. The elements 
most essential for plant growth are potassium, calcium, 
magnesium, iron, phosphorus, and sulphur.^ 

In the animal body minerals are derived, either di- 
rectly or indirectly, from the vegetable foods consumed. 



GENERAL COMPOSITION OF FOODS 5 

The part which each of the mineral elements takes in 
animal nutrition is not well understood. Some of the 
elements, as phosphorus and sulphur, are in organic 
combination with the nitrogenous compounds, as the 
nucleated albuminoids, which are very essential for ani- 
mal life. In both plant and animal bodies, the mineral 
matter is present as mineral salts and organic combina- 
tions. It is held that the ash elements which are in 
organic combination are the forms mainly utilized for 
tissue construction. While it is not known just what 
part all the mineral elements take in animal nutrition, 
experiments show that in all ordinary mixed rations the 
amount of the different mineral elements is in excess 
of the demands of the body, and it is only in rare 
instances, as in cases of restricted diet, or convalescence 
from, some disease, that special attentioh need be given 
to increasing the mineral content of the ration. An ex- 
cess of mineral matter in foods is equally as objection- 
able as a scant amount, elimination of the excess entail- 
ing additional work on the body. 

The composition of the ash of different food mate- 
rials varies widely, both in amount, and form of the 
individual elements. When for any reason it is neces- 
sary to increase the phosphates in a ration, milk and 
eggs do this to a greater extent than almost any other 
foods. Common salt, or sodium chloride, is one of the 
most essential of the mineral constituents of the body. 
It is necessary for giving the blood its normal composi- 
tion, furnishing acid and basic constituents for the pro- 



6 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

ductioii of the digestive fluids, and for the nutrition 
of the cells. While salt is a necessary food, in large 
amounts, as when the attempt is made to use sea water 
as a beverage, it acts as a poison, suggesting that a ma- 
terial may be both a food and a poison. When sodium 
chloride is entirely withheld from an animal, death 
from salt starvation ensues. Many foods contain natu- 
rally small amounts of sodium chloride. 

4. Organic Matter. — That portion of a food material 
which is converted into gaseous or volatile products 
during combustion is called the organic matter. It is 
a mechanical mixture of compounds made up of car- 
bon, hydrogen, oxygen, nitrogen, and sulphur, and is 
composed of various individual organic compounds, as 
cellulose, starch, sugar, albumin, and fat. The amount 
in a food is determined by subtracting the ash and 
water from lOO. The organic matter varies widely in 
composition ; in some foods it is largely starch, as in 
potatoes and rice, while in others, as forage crops con- 
sumed by animals, cellulose predominates. The na- 
ture of the prevailing organic compound, as sugar or 
starch, determines the nutritive value of a food. Each 
has a definite chemical composition capable of being 
expressed by a formula. Considered collectively, the 
organic compounds are termed organic matter. When 
burned, the organic compounds are converted into 
gases, the carbon uniting with the oxygen of the air 
to form carbon dioxide, hydrogen to form water, sul- 



GENERAL COMPOSITION OF FOODS 7 

phur to form sulphur dioxide, and the nitrogen to form 
oxides of nitrogen and ammonia. 

5. Classification of Organic Compounds. — All food 
materials are composed of a large number of organic 
compounds. For purposes of study these are divided 
into classes. The element nitrogen is taken as the 
basis of the division. Compounds which contain this 
element are called nitrogenous, while those from which 
it is absent are called non-nitrogenous.^ The nitroge- 
nous organic compounds are composed of the elements 
nitrogen, hydrogen, carbon, oxygen, and sulphur, while 
the non-nitrogenous compounds are composed of carbon, 
hydrogen, and oxygen. In vegetable foods the non- 
nitrogenous compounds predominate, there being usually 
from six to twelve parts of non-nitrogenous to every one 
part of nitrogenous, while in animal foods the nitroge- 
nous compounds are present in larger amount. 

NON-NITROGENOUS COMPOUNDS 

6. Occurrence. — The non-nitrogenous compounds of 
foods consist mainly of cellulose, starch, sugar, and fat. 
For purposes of study, they are divided into subdivi- 
sions, as carbohydrates, pectose substances or jellies, 
fats, organic acids, essential oils, and mixed compounds. 
In plants the carbohydrates predominate, while in ani- 
mal tissue the fats are the chief non-nitrogenous con- 
stituents. 



5 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

7. Carbohydrates. — This term is applied to a class 
of compounds similar in general composition, but dif- 
fering widely in structural composition and physical 
properties. Carbohydrates make up the bulk of vege- 
table foods and, except in milk, are found only in traces 
in animal foods. They are all represented by the 
general formula CH^nO,,, there being twice as many 
hydrogen as oxygen atoms, the hydrogen and oxygen 
being present in the same proportion as in water. As 
a class, the carbohydrates are neutral bodies, and, when 
burned, form carbon dioxide and water. 

8. Cellulose is the basis of the cell structure of plants, 
and is found in various physical forms in food ma- 
terials.^ Sometimes it is hard and dense, resisting 
digestive action and mechanically inclosing other nutri- 
ents and thus preventing their being 
available as food. In the earlier 
stages of plant growth a part of the 
cellulose is in chemical combination 
with water, forming hydrated cellu- 
lose, a portion of which undergoes 
digestion and produces heat and en- 
ergy in the body. Ordinarily, how- 

FiG. 2. — Cellular ever, cellulose adds but little in the 

Structure of ^^y Qf nutritive value, althou^^h it is 
Plant Cell. -^ ^ 

often beneficial mechanically and im- 
parts bulk to some foods otherwise too concentrated. 
The mechanical action of cellulose on the digestion of 




GENERAL COMPOSITION OF FOODS 9 

food is discussed in Chapter XV. Cellulose usually 
makes up a very small part of human food, less than i 
per cent. In refined white flour there is less than .05 
of a per cent; in oatmeal and cereal products from .5 
to I per cent, depending upon the extent to which the 
hulls are removed, and in vegetable foods from .1 to i 
per cent. The cellulose content of foods is included in 
the crude fiber of the chemist's report. 

9. Starch occurs widely distributed in nature, par- 
ticularly in the seeds, roots, and tubers of some plants. 
It is formed in the leaves of plants as a result of the 
joint action of chlorophyll and protoplasm, and is gen- 
erally held by plant physiologists to be the first com- 
pound produced in the plant cell. Starch is composed 
of a number of overlapping layers separated by starch 
cellulose ; between these layers the true starch or amy- 
lose is found. Starch from the various cereals and 
vegetables differs widely in mechanical structure ; in 
wheat it is circular, in corn somewhat angular, and in 
parsnips exceedingly small, while potato starch granules 
are among the largest.'^ The nature of starch can be 
determined largely from its mechanical structure as 
studied under the microscope. It is insoluble in cold 
water because of the protecting action of the cellular 
layer, but on being heated it undergoes both mechanical 
and chemical changes ; the grains are partially ruptured 
by pressure due to the conversion into steam of the 
moisture held mechanically. The cooking of foods is 



TO HUMAN FOODS AND THEIR NUTRITIVE VALUE 

beneficial from a mechanical point of view, as it results 
in partial disintegration of the starch masses, changing 
the structure so that the starch is more readily acted 
upon by the ferments of the digestive tract. At a 
temperature of about 120° C. starch begins to undergo 
chemical change, resulting in the rearrangement of the 
atoms in the molecule with the production of dextrine 
and soluble carbohydrates. Dextrine is formed on the 
crust of bread, or whenever potatoes or starchy foods 
are browned. At a still higher temperature starch is 
decomposed, with the liberation of water and production 
of compounds of higher carbon content. When heated in 
contact with water, it undergoes hydration changes ; gelati- 
nous-like products are formed, which are finally converted 
into a soluble condition. In cooking cereals, the hydra- 
tion of the starch is one of the main physical and 
chemical changes that takes place, and it simply results 
in converting the material into such a form that other 
chemical changes may more readily occur. Before 
starch becomes dextrose, hydration is necessary. If 
this is accomplished by cooking, it saves the body just 
so much energy in digestion. Many foods owe their 
value largely to the starch. In cereals it is found to 
the extent of 72 to 'jG per cent ; in rice and potatoes in 
still larger amounts ; and it is the chief constituent of 
many vegetables. When starch is digested, it is first 
changed to a soluble form and then gradually undergoes 
oxidation, resulting in the production of heat and energy, 
the same products — carbon dioxide and water — being 



GENERAL COMPOSITION OF FOODS II 

formed as when starch is burned. Starch is a valu- 
able heat-producing nutrient; a pound yields i860 
calories. See Chapter XV. 

10. Sugar. — Sugars are widely distributed in nature, 
being found principally in the juices of the sugar cane, 
sugar beet, and sugar maple. They are divided into 
two large classes : the sucrose group and the dextrose 
group, the latter being produced from sucrose, starch, 
and other carbohydrates by inversion and allied chemi- 
cal changes. Because of the importance of sugar in 
the dietary, Chapter V is devoted to the subject. 

11. Pectose Substances are jelly-like bodies found in 
fruits and vegetables. They are closely related in 
chemical composition to the carbohydrates, into which 
form they are changed during digestion ; -and in nutri- 
tion they serve practically the same function. In the 
early stages of growth the pectin bodies are combined 
with organic acids, forming insoluble compounds, as the 
pectin in green apples. During the ripening of fruit 
and the cooking of vegetables, the pectin is changed to 
a more soluble and digestible condition. In food analy- 
sis, the pectin is usually included with the carbohy- 
drates. 

12. Nitrogen-free-extract. — In discussing the com- 
position of foods, the various non-nitrogenous com- 
pounds, as starch, sugar, and pectin, are grouped under 
the name of nitrogen-free-extract. Methods of chemi- 



12 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

cal analysis have not yet been sufficiently perfected to 
enable accurate and rapid determination to be made of 
all these individual carbohydrates, and hence they are 
grouped together as nitrogen-free-extract. As the 
name indicates, they are compounds which contain no 
nitrogen, and are extractives in the sense that they are 
soluble in dilute acid and alkaline solutions. The nitro- 
gen-free-extract is determined indirectly, that is, by the 
method of difference. All the other constituents of a 
food, as water, ash, crude fiber (cellulose), crude protein, 
and ether extract, are determined ; the total is subtracted 
from lOO, and the difference is nitrogen -free-extract. 
In studying the nutritive value of foods, particular 
attention should be given to the nature of the nitrogen- 
free-extract, as in some instances it is composed of 
sugar and in others of starch, pectin, or pentosan (gum 
sugars). While all these compounds have practically 
the same fuel value, they differ in composition, struc- 
ture, and the way in which they are acted upon by 
chemicals and digestive ferments.^ 

13. Fat. — Fat is found mainly in the seeds of plants, 
but to some extent in the leaves and stems. It differs 
from starch in containing more carbon and less oxygen. 
In starch there is about 44 per cent of carbon, while in 
fat there is 75 per cent. Hence it is that when fat is 
burned or undergoes combustion, it yields a larger 
amount of the products of combustion — carbon dioxid 
and water — than does starch. A gram of fat produces 



GENERAL COMPOSITION OF FOODS 



13 



2J times as much heat as a gram of starch. Fat is 
the most concentrated non-nitrogenous nutrient. As 
found in food mate- 
rials, it is a mechani- 
cal mixture of various 
fats, among which are 
stearin, palmitin, and 
olein. Stearin and 
palmitin are hard fats, 
crystalline in struc- 
ture, and with a high 
melting point, while 
olein is a liquid. In ad- 
dition to these three, 
there are also small 
amounts of other fats, 
as butyrin in butter, 
which give character 
or individuality to ma- 
terials. There are a 
number of vegetable 
fats or oils which are 
used for food pur- 
poses and, when prop- 
erly prepared and 
refined, have a high 
nutritive value. Occa- 
sionally one fat of cneaper origin but not necessarily of 
lower nutritive value is substituted for another. The 




Fig. 3. 



Apparatus used for the Deter- 
mination OF Fat. 



14 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

fats have definite physical and chemical properties which 
enable them to be readily distinguished, as iodine num- 
ber, specific gravity, index of refraction, and heat of com- 
bustion. By iodine number is meant the percentage of 
iodine that will unite chemically with the fat. Wheat oil 
has an iodine number of about lOO, meaning that one 
pound of wheat oil will unite chemically with one pound 
of iodine. Fats have a lower specific gravity than water, 
usually ranging from .89 to .94, the specific gravity of 
a fat being fairly constant. All fats can be separated 
into glycerol and a fatty acid, glycerol or glycerine being 
common constituents, while each fat yields its own 
characteristic acid, as stearin, stearic acid ; palmitin, 
palmitic acid ; and olein, oleic acid. The fats are 
soluble in ether, chloroform, and benzine. In the 
chemical analysis of foods, they are separated with 
ether, and along with the fat, variable amounts of other 
substances are extracted, these extractive products 
usually being called " ether extract " or " crude fat." ^ 
The ether extract of plant tissue contains in addition to 
fat appreciable amounts of cellulose, gums, coloring, and 
other materials. From cereal products the ether extract 
is largely fat, but in some instances lecithin and other 
nitrogenous fatty substances are present, while in animal 
food products, as milk and meat, the ether extract is 
nearly pure fat. 

14. Organic Acids. — Many vegetable foods contain 
small amounts of organic acids, as malic acid found in 



GENERAL COMPOSITION OF FOODS 15 

apples, citric in lemons, and tartaric in grapes. These 
give characteristic taste to foods, but have no direct 
nutritive value. They do not yield heat and energy as 
do starch, fat, and protein ; they are, however, useful for 
imparting flavor and palatabiHty, and it is believed they 
promote to some extent the digestion of foods with 
which they are combined by encouraging the secretion 
of the digestive fluids. Many fruits and vegetables owe 
their dietetic value to the organic acids which they con- 
tain. In plants they are usually in chemical combina- 
tion with the minerals, forming compounds as salts, or 
with the organic compounds, producing materials as 
acid proteins. In the plant economy they take an 
essential part in promoting growth and aiding the plant 
to secure by osmotic action its mineral food from the 
soil. Organic acids are found to some extent in animal 
foods, as the various lactic acids of meat and milk. 
They are also formed in food materials as the result of 
ferment action. When seeds germinate, small amounts 
of carbohydrates are converted into organic acids. In 
general the organic acids are not to be considered as 
nutrients, but as food adjuncts, increasing palatabiHty 
and promoting digestion. 

15. Essential Oils. — Essential or volatile oils differ 
from fats, or fixed oils, in chemical composition and 
physical properties.^ The essential oils are readily 
volatilized, leaving no permanent residue, while the 
fixed fats are practically non-volatile. Various essen- 



l6 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

tial oils are present in small amounts in nearly all 
vegetable food materials, and the characteristic flavor 
of many fruits is due to them. It is these compounds 
which are used for flavoring purposes, as discussed in 
Chapter IV. The amount in a food material is very 
small, usually only a few hundredths of a per cent. 
The essential oils have no direct food value, but in- 
directly, like the organic acids, they assist in promoting 
favorable digestive action, and are also valuable because 
they impart a pleasant taste. Through poor methods of 
cooking and preparation, the essential oils are readily 
lost from some foods. 

16. Mixed Compounds. — Food materials frequently 
contain compounds which do not naturally fall into the 
five groups mentioned, — carbohydrates, pectose sub- 
stances, fats, organic acids, and essential oils. The 
amount of such compounds is small, and they are classed 
as miscellaneous or mixed non-nitrogenous compounds. 
Some of them may impart a negative value to the food, 
and there are others which have ah the characteristics, 
as far as general composition is concerned, of the non- 
nitrogenous compounds, but contain nitrogen, although 
as a secondary rather than an essential constituent. 

17. Nutritive Value of Non-nitrogenous Compounds. — 

The non-nitrogenous compounds, taken as a class, are 
incapable alone of sustaining life, because they do not 
contain any nitrogen, and this is necessary for produc- 



GENERAL COMPOSITION OF FOODS 1 7 

ing proteid material in the animal body. They are 
valuable for the production of heat and energy, and 
when associated with the nitrogenous compounds, are 
capable of forming non-nitrogenous reserve tissue. It 
is equally impossible to sustain life for any prolonged 
period with the nitrogenous compounds aione. It is 
when these two classes are properly blended and 
naturally united in food materials that their main value 
is secured. For nutrition purposes they are mutually 
related and dependent. Some food materials contain 
the nitrogenous and non-nitrogenous compounds blended 
in such proportion as to enable one food alone to prac- 
tically sustain life, while in other cases it is necessary, 
in order to secure the best results in the feeding of 
animals and men, to combine different foods varying in 
their content of these two classes of compounds.'^ 

NITROGENOUS COMPOUNDS 

18. General Composition. — The nitrogenous com- 
pounds are more complex in composition than the non- 
nitrogenous. They are composed of a larger number 
of elements, united in different ways so as to form a 
much more complex molecular structure. Foods con- 
tain numerous nitrogenous organic compounds, which, 
for purposes of study, are divided into four divisions, — 
proteids, albuminoids, amids, and alkaloids. In addition 
to these, there are other nitrogenous compounds which 
do not naturally fall into any one of the four divisions, 
c 



1 8 HUMAN FOODS AND THEIR NUTRITIVE VALUE 




Fig. 



Apparatus used for Determining Total Nitrogen and 
Crude Protein in Foods. 



The material is digested in the flask (3) with sulphu;ic acid and the organic 
nitrogen converted into ammonium sulphate, which is later liberated and 
distilled at i, and the ammonia neutralized with standard acid (2). 



GENERAL COMPOSITION OF FOODS 1 9 

Also in some foods there are small amounts of nitrogen 
in mineral forms, as nitrates and nitrites. 

19. Protein. — The term " protein " is applied to a large 
class of nitrogenous compounds resembling each other 
in general composition, but differing widely in structural 
composition. As a class, the proteins contain about i6 
per cent of nitrogen, 52 per cent of carbon, from 6 to 7 
per cent of hydrogen, 22 per cent of oxygen, and less 
than 2 per cent of sulphur. These elements are com- 
bined in a great variety of ways, forming various groups 
or radicals. In studying the protein molecule a large 
number of derivative products have been observed, as 
amid radicals, various hydrocarbons, fatty acids, and 
carbohydrate-like bodies.^ It would appear that in the 
chemical composition of the proteins there, are all the 
constituents, or simpler products, of the non-nitrogenous 
compounds, and these are in chemical combination with 
amid radicals and nitrogen in various forms. The nitro- 
gen of many proteids appears to be present in more 
than one form or radical. The proteids take an im- 
portant part in life processes. They are found more 
extensively in animal than in plant bodies. The pro- 
toplasm of both the plant and animal cell is composed 
mainly of protein. 

Proteids are divided into various subdivisions, as 
albumins, globuhns, albuminates, proteoses and pep- 
tones, and insoluble proteids. In plant and animal 
foods a large amount of the protein is present as in- 



20 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

soluble proteids ; that is, they are not dissolved by sol- 
vents, as water and dilute salt solution. The albumins 
are soluble in water and coagulated by heat at a tem- 
perature of 157° to 161° F. Whenever a food material 
is soaked in water, the albumin is removed and can 
then be coagulated by the action of heat, or of chemi- 
cals, as tannic acid, lead acetate, and salts of mercury. 
The globulins are proteids extracted from food materials 
by dilute salt solution after the removal of the albumins. 
Globulins also are coagulated by heat and precipitated 
by chemicals. The amount of globuhns in vegetable 
foods is small. In animal foods myosin and vitellin, 
found in the yolk of the egg, and some of the proteids 
of the blood, are examples of globulins. Albuminates 
are casein-like proteids found in both animal and vege- 
table foods. They are supposed to be proteins that are 
in feeble chemical combination with acid and alkaline 
compounds, and they are sometimes called acid and 
alkali proteids. Some are precipitated from their solu- 
tions by acids and others by alkalies. Peas and beans 
contain quite large amounts of a casein-like proteid 
called legumin. Proteoses and peptones are proteins 
soluble in water, but not coagulated by heat. They 
are produced from other proteids by ferment action 
during the digestion of food and the germination of 
seeds, and are often due to the changes resulting from 
the action of the natural ferments or enzymes inherent 
in the food materials. As previously stated, the insolu- 
ble proteids are present in far the largest amount of any 



GENERAL COMPOSITION OF FOODS 21 

of the nitrogenous materials of foods. Lean meat and 
the gluten of wheat and other grains are examples of 
the insoluble proteids. The various insoluble proteids 
from different food materials each has its own compo- 
sition and distinctive chemical and physical properties, 
and from each a different class and percentage amount 
of derivative products are obtained. ^ While in general 
it is held that the various proteins have practically the 
same nutritive value, it is possible that because of differ- 
ences in structural composition and the products formed 
during digestion there may exist notable differences in 
nutritive value. During digestion the insoluble pro- 
teids undergo an extended series of chemical changes. 
They are partially oxidized, and the nitrogenous portion 
of the molecule is eliminated mainly in the form of 
amids, as urea. The insoluble proteins constitute the 
main source of the nitrogenous food supply of both 
humans and animals. 

20. Crude Protein. — In the analysis of foods, the 
term "crude protein" is used to designate the total 
nitrogenous compounds considered collectively ; it is 
composed largely of protein, but also includes the 
amids, alkaloids, and albuminoids. " Crude protein " 
and ** total nitrogenous compounds" are practically 
synonymous terms. The various proteins all contain 
about 1 6 per cent of nitrogen ; that is, one part of nitro- 
gen is equivalent to 5.25 parts of protein. In analyzing 
a food material, the total organic nitrogen is determined 



2 2 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

and the amount multiplied by 6.25 to obtain the crude 
protein. In some food materials, as cereals, the crude 
protein is largely pure protein, while in others, as pota- 
toes, it is less than half pure protein, the larger portion 
being amids and other compounds. In comparing the 
crude protein content of one food with that of another, 
the nature of both proteids should be considered and also 
the amounts of non-proteid constituents. The factor 
6.25 for calculating the protein equivalent of foods is 
not strictly appHcable to all foods. For example, the 
proteids of wheat — gliadin and glutenin — contain over 
18 per cent of nitrogen, making the nitrogen factor 
about 5.68 instead of 6.25. If wheat contains 2 per 
cent of nitrogen, it is equivalent to 12.5 per cent of 
crude protein, using the factor 6.25 ; or to 11.4, using 
the factor 5.7. The nitrogen content of foods is abso- 
lute ; the protein content is only relative.^ 

21. Food Value of Protein. — Because of its complex- 
ity in composition, protein is capable of being used by 
the body in a greater variety of ways than starch, sugar, 
or fat. In addition to producing heat and energy, pro- 
tein serves the unique function of furnishing material 
for the construction of new muscular tissue and the repair 
of that which is worn out. It is distinctly a tissue-build- 
ing nutrient. It also enters into the composition of all 
the vital fluids of the body, as the blood, chyme, chyle, 
and the various digestive fluids. Hence it is that pro- 
tein is required as a nutrient by the animal body, and it 



GENERAL COMPOSITION OF FOODS 23 

cannot be produced from non-nitrogenous compounds. 
In vegetable bodies, the protein can be produced syn- 
thetically from amids, which in turn are formed from 
ammonium compounds. While protein is necessary in 
the ration, an excessive amount should be avoided. 
When there is more than is needed for functional pur- 
poses, it is used for heat and energy, and as foods rich 
in protein are usually the most expensive, an excess adds 
unnecessarily to the cost of the ration. Excess of pro- 
tein in the ration may also result in a diseased condition, 
due to imperfect eUmination of the protein residual prod- 
ducts from the body.^^ 

22. Albuminoids differ from proteids in general com- 
position and, to some extent, in nutritive value. They 
are found in animal bodies mainly in the connective 
tissue and in the skin, hair, and nails. Some 'of the albu- 
minoids, as nuclein, are equal in food value to protein, 
while others have a lower food value. In general, 
albuminoids are capable of conserving the protein of 
the body, and hence are called " protein sparers," but 
they cannot in every way enter into the composition of 
the body, as do the true proteins. 

23. Amids and Amines. — These are nitrogenous 
compounds of simpler structure than the proteins and 
albuminoids. They are sometimes called compound 
ammonia in that they are derived from ammonia by the re- 
placement of one of the hydrogen atoms with an organic 
radical. In plants, amids are intermediate compounds 



24 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

in the production of the proteids, and in some vegetables 
a large portion of the nitrogen is amids. In animal 
bodies amids are formed during oxidation, digestion, 
and disintegration of proteids. It is not definitely known 
whether or not a protein in the animal body when 
broken down into amid form can again be reconstructed 
into protein. The amids have a lower food value than 
the proteids and albuminoids. It is generally held that, 
to a certain extent, they are capable, when combined 
with proteids, of preventing rapid conversion of the 
body proteid into soluble form. When they are used 
in large amounts in a ration, they tend to hasten oxida- 
tion rather than conservation of the proteids. 

24. Alkaloids. — In some plant bodies there are small 
amounts of nitrogenous compounds called alkaloids. 
They are not found to any appreciable extent in food 
plants. The alkaloids, like ammonia, are basic in 
character and unite with acids to form salts. Many 
medicinal plants owe their value to the alkaloids which 
they contain. In animal bodies alkaloids are formed 
when the tissue undergoes fermentation changes, and 
also during disease, the products being known as 
ptomaines. Alkaloids have no food value, but act 
physiologically as irritants on the nerve centers, making 
them useful from a medicinal rather than from a nutri- 
tive point of view. To medical and pharmaceutical 
students the alkaloids form a very important group of 
compounds. 



GENERAL COMPOSITION OF FOODS 



25 



25. General Relationship of the Nitrogenous Com- 
pounds. — Among the various subdivisions of the nitroge- 
nous compounds there exists a relationship similar to 
that among the non-nitrogenous compounds. From 




I 2 3 4 5 (> 

Fig. 5. — Graphic Composition of Flour. 
I, flour; 2, starch ; 3, gluten ; 4, water ; 5, fat ; 6, ash. 



proteids, amids and alkaloids may be formed, just as 
invert sugars and their products are formed from 
sucrose. Although glucose products are derived from 
sucrose, it is not possible to reverse the process and 
obtain sucrose or cane sugar from starch. So it is with 
proteins, while the amid may be obtained from the 



26 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

proteid in animal nutrition, as far as known the process 
cannot be reversed and proteids be obtained from amids. 
In the construction of the protein molecule of plants, 
nitrogen is absorbed from the soil in soluble forms, as 
compounds of nitrates and nitrites and ammonium salts. 
These are converted, first, into amids and then into 
proteids. In the animal body just the reverse of this 
process takes place, — the protein of the food under- 
goes a series of changes, and is finally eliminated from 
the body as an amid, which in turn undergoes oxidation 
and nitrification, and is converted into nitrites, nitrates, 
and ammonium salts. These forms of nitrogen are then 
ready to begin again in plant and animal bodies the 
same cycle of changes. Thus it is that nitrogen may 
enter a number of times into the composition of plant 
and animal tissues. Nature is very economical in her 
use of this element.^ 



CHAPTER II 

CHANGES IN COMPOSITION OF FOODS DURING COOK- 
ING AND PREPARATION 

26. Raw and Cooked Foods Compared. — Raw and 

cooked foods differ in chemical composition mainly in 
the content of water. The amount of nutrients on a 
dry matter basis is practically the same, but the struc- 
tural composition is affected by cooking, and hence it 
is that a food prepared for the table often differs 
appreciably from the raw material. Cooked meat, for 
example, has not the same percentage and 'structural 
composition as raw meat, although the difference in 
nutritive value between a given weight of each is not 
large. During cooking, foods are acted upon chemi- 
cally, physically, and bacteriologically, and it is usually 
the joint action of these three agencies that brings about 
the desirable changes incident to their preparation for 
the table. 

27. Chemical Changes during Cooking. — Each of the 
chemical compounds of which foods are composed is 
influenced to a greater or less extent by heat and 
modified in composition. The chemistry of cooking is 
mainly a study of the chemical changes that take place 
when compounds, as cellulose, starch, sugar, pectin, fat, 

27 



28 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

and the various proteids, are subjected to the joint 
action of heat, moisture, air, and ferments. The changes 
which affect the cellulose are physical rather than 
chemical. A slight hydration of the cellular tissue, 
however, does take place. In human foods cellulose is 
not found to any appreciable extent. Many vegetables, 
as potatoes, which are apparently composed of cellular 
substances, contain but little true cellulose. Starch, as 
previously stated, undergoes hydration in the presence 
of water, and, at a temperature of 120° C, is converted 
into dextrine. At a higher temperature disintegration 
of the starch molecule takes place, with the formation 
of carbon monoxid, carbon dioxid, and water, and the 
production of a residue richer in carbon than is starch. 
On account of the moisture, the temperature in many 
cooking operations is not sufficiently high for changes 
other than hydration and preliminary dextrinizing. In 
Chapter XI is given a more extended account of the 
changes affecting starch which occur in bread making. 

During the cooking process sugars undergo inversion 
to a slight extent. That is, sucrose is converted into 
levulose and dextrose sugars. At a higher temperature, 
sugar is broken up into its constituents — water and 
carbon dioxide. The organic acids which many fruits 
and vegetables contain hasten the process of inversion. 
When sugar is subjected to dry heat, it becomes a brown, 
caramel-like material sometimes called barley sugar. 
During cooking, sugars are not altered in solubility or 
digestibility ; starches, however, are changed to a more 



CHANGES IN FOODS DURING COOKING 29 

soluble form, and pectin — a jelly-like substance — is 
converted from a less to a more soluble condition, as 
stated in Chapter I. Changes incident to the cooking 
of fruits and vegetables rich in pectin, as in the making 
of jellies, are similar to those which take place in the 
last stages of ripening. 

The fats are acted upon to a considerable extent by 
heat. Some of the vegetable oils undergo slight oxida- 
tion, resulting in decreased solubility in ether, but since 
there is no volatilization of the fatty matter, it is a 
change that does not materially affect the total fuel 
value of the food.^^ 

There is a general tendency for the proteids to be- 
come less soluble by the action of heat, particularly the 
albumins and globulins. The protein molecule dissoci- 
ates at a high temperature, with formation of volatile 
products, and therefore foods rich in protein should not 
be subjected to extreme heat, as losses of food value 
may result. During cooking, proteids undergo hydra- 
tion, which is necessary and preliminary to digestion, 
and the heating need be carried only to this point, and 
not to the splitting up of the molecule. Prolonged high 
temperature in the cooking of proteids and starches is 
unnecessary in order to induce the desired chemical 
changes. When these nutrients are hydrated, they are 
in a condition to undergo digestion, without the body 
being compelled to expend unnecessary energy in bring- 
ing about this preliminary change. Hence it is that, 
while proper cooking does not materially affect the total 



so 



HUMAN FOODS AND THEIR NUTRITIVE VALUE 



digestibility of proteids or starches, it influences ease of 
digestion, as well as conserves available energy, thereby 
making more economical use of these nutrients. 




28. Physical Changes. — The mechanical structure of 
foods is influenced by cooking to a greater extent than 
is the chemical composition. One of the chief objects 
of cooking is to bring the food into better mechanical 
condition for digestion. ^^ Heat and water cause partial 
disintegration of both animal and vegetable tissues. 
The cell-cementing materials are weakened, and a sof- 
tening of the tissues 
results. Often the 
action extends still 
further in vegetable 
foods, resulting in 
disintegration of the 
individual starch 
granules. When 
foods are subjected 
to dry heat, the mois- 
ture they contain is 
converted into 
steam, which causes 
bursting of the tis- 
sues. A good ex- 
ample of this is the popping of corn. Heat may 
result, too, in mechanical removal of some of the 
nutrients, as the fats, which are liquefied at temperatures 



Fig. 6. 



-Cells of a Partially Cooked 
Potato. (After Konig.) 



CHANGES IN FOODS DURING COOKING 



31 



ranging from 100° to 200 F. Many foods which in the 
raw state contain quite large amounts of fat, lose a por- 
tion mechanically during cooking, as is the case with 
bacon when it is cut in thin slices and fried or baked 
until crisp. When foods are boiled, the natural juices 
being of somewhat different density from the water in 
which they are cooked, slight osmotic changes occur. 
There is a tendency toward equalization of the compo- 
sition of the juices of the food and the water in which 
they are cooked. In order to achieve the best mechani- 
cal effects in cooking, high temperatures are not neces- 
sary, except at first for rupturing the tissues ; softening 
of the tissues is best 
effected by prolonged 
and slow heat. At a 
higher temperature 
many of the volatile 
and essential oils are 
lost, while at lower 
temperatures these 
are retained and in 
some instances 
slightly developed. 
The cooking should 
be sufficiently pro- 
longed and the tem- 
perature high enough 
to effectually disintegrate and soften a 
but not to cause extended chemical changes. 




Fig. 7. — Cells of Raw Potato, showing 
Starch Gralxs. (After Konig.) 



of the tissues 



32 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

There is often an unnecessarily large amount of heat 
lost through faulty construction of stoves and lack of 
judicious use of fuels, which greatly enhances the cost 
of preparing foods. Ovens are frequently coated with 
deposits of soot ; this causes the heat to be thrown out 
into the room or lost through the chimney, rather than 
utilized for heating the oven. In an ordinary cook stove 
it is estimated that less than 7 per cent of the heat and 
energy of the fuel is actually employed in bringing about 
physical and chemical changes incident to cooking.^^ 

29. Bacteriological Changes. — The bacterial organ- 
isms of foods are destroyed in the cooking, provided a 
temperature of 150° F. is reached and maintained for 
several minutes. The interior of foods rarely reaches 
a temperature above 200° F., because of the water they 
contain which is not completely removed below 212°. 
One of the chief objects in cooking food is to render 
it sterile. Not only do bacteria become innocuous 
through cooking, but various parasites, as trichina and 
tapeworm, are destroyed, although some organisms can 
live at a comparatively high temperature. Cooked foods 
are easily re-inoculated, in some cases more readily than 
fresh foods, because they are in a more disintegrated 
condition. 

In many instances bacteria are of material assistance 
in the preparation of foods, as in bread making, butter 
making, curing of cheese, and ripening of meat. All 
the chemical compounds of which foods are composed 



CHANGES IN FOODS DURING COOKING 33 

are subject to fermentation, each compound being acted 
upon by its special ferment body. Those which convert 
the proteids into soluble form, as the peptonizing fer- 
ments, have no action upon the carbohydrates. A cycle 
of bacteriological changes often takes place in a food 
material, one class of ferments working until their prod- 
ucts accumulate to such an extent as to prevent their 
further activity, and then the process is taken up by 
others, as they find the conditions favorable far devel- 
opment. This change of bacterial flora in food mate- 
rials is akin to the changes in the vegetation occupying 
soils. In each case, there is a constant struggle for 
possession. Bacteria take a much more important part 
in the preparation of foods than is generally considered. 
As a result of their workings, various chemical products, 
as organic acids and aromatic compounds, are produced. 
The organic acids chemically unite with the nutrients of 
foods, changing their composition and physical proper- 
ties. Man is, to a great extent, dependent upon bacterial 
action. Plant Hfe also is dependent upon the bacterial 
changes which take place in the soil and in the plant tis- 
sues. The stirring of seeds into activity is apparently 
due to enzymes or soluble ferments which are inherent 
in the seed. A study of the bacteriological changes 
which foods undergo in their preparation and digestion 
more properly belongs to the subject of bacteriology, 
and in this work only brief mention is made of some of 
the more important parts which microorganisms take 
in the preparation of foods, 



34 HUMAN FOODS AND THEIR NUTRITIVE VALUE 






30. Insoluble Ferments. — Insoluble ferments are mi- 
nute, plant-like bodies of definite form and structure, and 

can be studied only with the micro- 
scope.^ They are developed from 
spores or seeds, or from the split- 
ting or budding of the parent cells. 
Under suitable conditions they mul- 
FIG. 8.- LACTIC ACID t^P^y rapidly, deriving the energy for 
Bacteria, much their life processes from the chemical 
Russ^lTr ^^^''' changes which they induce. For ex- 
ample, in the souring of milk the 
milk sugar is changed by the lactic acid ferments into 
lactic acid. In causing chemical changes, the ferment 
gives none of its own material to the reacting substance. 
These ferment bodies undergo life processes similar to 
plants of a higher order. 

All foods contain bacteria or ferments. In fact, it is 
impossible for a food stored and prepared under ordi- 
nary conditions, unless it has been specially treated, to 
be free from them. Some of them are useful, some are 
injurious, while others are capable of producing disease. 
The objectionable bacteria are usually destroyed by the 
joint action of sunlight, pure air, and water. 

31. Soluble Ferments. — Many plant and animal cells 
have the power of secreting substances soluble in water 
and capable of producing fermentation changes ; to 
these the term *' soluble ferments," or ''enzymes," is 
applied. These ferments have a cell structure like the 



CHANGES IX FOODS DURING COOKING « 35 

organized ferments. When germinated seed, as malted 
barley, is extracted, a soluble and highly nitrogenous 
substance, called the diastase ferment, is secured that 
changes starch into soluble forms. The soluble fer- 
ments induce chemical change by causing molecular 
disturbance or splitting up of the organic compounds, 
resulting in the production of derivative products. They 
take an important part in animal and plant nutrition, 
as by their action insoluble compounds are brought into 
a soluble condition so they can be utilized for nutritive 
purposes. In many instances ferment changes are due 
to the joint action of soluble and insoluble ferments. 
The insoluble ferment secretes an enzyme which in- 
duces a chemical change, modified by the further action 
of the soluble ferment. Many of the enzymes carry on 
their work at a low temperature, as in the curing of 
meat and cheese in cold storage. ^^ 

32. General Relationship of Chemical, Physical, and 
Bacteriological Changes. — It cannot be said that the 
beneficial results derived from the cooking of foods 
are due to either chemical, physical, or bacteriological 
change alone, but to the joint action of the three. In 
order to secure a chemical change, a physical change 
must often precede, and a bacteriological change can- 
not take place without causing a change in chemical com- 
position ; the three are closely related and interdependent. 

33. Esthetic Value of Foods. — Foods should be not 
only of good physical texture and contain the requisite 



36 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

nutrients, but they should also be pleasing to the eye 
and served in the most attractive manner. Some foods 
owe a part of their commercial value to color, and when 
they are lacking in natural color they are not consumed 
with a relish. There is no objection to the addition of 
coloring matter to foods, provided it is of a non-injurious 
character and does not affect the amount of nutrients, 
and that its presence and the kind of coloring material 
are made known. Some foods contain objectionable 
colors which are eliminated during the process of manu- 
facture, as in the case of sugar and flour. As far as re- 
moval of coloring matter from foods during refining is 
concerned, there can be no objection, so long as no inju- 
rious reagents or chemicals are retained, as the removal of 
the color in no way affects the nutritive value or permits 
fraud, but necessitates higher purification and refining. 
The use of chemicals and reagents in the preparation and 
refining of foods is considered permissible in all cases 
where the reagents are removed by subsequent processes. 
In the food decisions of the United States Department 
of Agriculture, it is stated : ** Not excluded under this pro- 
vision are substances properly used in the preparation 
of food products for clarification or refining and ehmi- 
nated in the further process of manufacture." ^^ 



CHAPTER III 
VEGETABLE FOODS 

34. General Composition. — Vegetable foods, with the 
exception of cereals, legumes, and nuts, contain a smaller 
percentage of protein than animal food products. They 
vary widely in composition and nutritive value; in some, 
starch predominates, while in others, sugar, cellulose, 
and pectin bodies are most abundant. The general 
term "vegetable foods" is used in this work to include 
roots, tubers, garden vegetables, cereals, legumes, and all 
prepared foods of vegetable origin. 

35. Potatoes contain about 75 per cent of water 
and 25 per cent of dry matter, the larger portion being 
starch. There is but Httle nitrogenous material in the 
potato, only 2.25 per cent, of which about half is in the 
form of proteids. There are ten parts of non-nitroge- 
nous substance to every one part of nitrogenous; or, 
in other words, the potato has a wide nutritive ratio, 
and as an article of diet needs to be supplemented 
with foods rich in protein. The mineral matter, cellu- 

37 



38 



HUMAN FOODS AND THEIR NUTRITIVE VALUE 



lar tissue, and fat in potatoes are small in amount, as 
are also the organic acids. Mechanically considered, 
the potato is composed of three parts, — outer skin, inner 
skin, and flesh. The layer immediately beneath the outer 
skin is slightly colored, and is designated the fibro-vascu- 

lar layer. The outer and inner 
skins combined make up about 
lo per cent of the weight of 
the potato. 

A large portion of the pro- 
tein of the potato is albumin, 
which is soluble in water. 
When potatoes are peeled, cut 
in small pieces, and soaked in 
water for several hours before 
boihng, 80 per cent of the crude 
protein, or total nitrogenous 
material, is extracted, render- 
ing the product less valuable 
as food. When potatoes are 
placed directly in boiling water, the losses of nitroge- 
nous compounds are reduced to about 7 per cent, and, 
when the skins are not removed, to i per cent. Di- 
gestion experiments show that 92 per cent of the starch 
and 72 per cent of the protein are digested. ^^ Com- 
pared with other foods, potatoes are often a cheap source 
of non-nitrogenous nutrients. If used in excessive 
amounts, however, they have a tendency to make the 
ration unbalanced and too bulky. 



/ .■ 


^-~ 


■ . \ 






\ 

\ 




d 


c h 


a 


v^ 




/ 




'^'-~ 





Fig. g. — Transverse Section 
OF Potato. (After Cowden 
and BUSSARD.) a, skin ; b, cor- 
tical layer; c, outer medullary 
layer ; d, inner medullary layer. 



VEGETABLE FOODS 
Mechanical Composition of the Potato 

Unpeeled potatoes 

Outer, or true skin 

Inner skin, or fibro-vascular layer * 

Flesh 



39 



Per Cent 

lOO.O 

2.5 

8.5 

890 



Chemical Composition of the Potato 







Carbohydrates 






Crude 




Nitro- 








Water 


Pro- 
tein 


Fat 


gen- 

free- 

extract 


Fiber 


Ash 




% 


% 


% 


% 


% 


% 


Outer, or true skin . . 


80.1 


2.7 


0.8 


14. 


6 


1.8 


Inner skin, or fibro- 














vascular layer . . 


83.2 


2-3 


O.I 


12.6 


0.7 


I.I 


Flesh 


81. 1 


2.0 


O.l 


157 


0-3 


0.8 


Average of 86 Ameri- 














can analyses f . . 


78.0 


2.2 


O.I 


18. 


8 


0.9 


Average of 11 8 Euro- 














pean analyses X . . 


75.0 


2.1 


0.1 


21.0 


0.7 


I.I 



36. Sweet Potatoes contain more dry matter than 
white potatoes, the difference being due mainly to the 
presence of about 6 per cent of sugar. There is approxi- 
mately the same starch content, but more fat, protein, 



* Including a small amount of flesh. 

t From an unpublished compilation of analyses of American food 
products. 

+ Konig, " Chemie der Nahrungs- und Genussmittel," 3d ed., II, p. 626. 



40 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

and fiber. As a food, they supply a large amount of 
non-nitrogenous nutrients. 

37. Carrots contain about half as much dry matter as 
potatoes, and half of the dry matter is sugar, nearly 
equally divided between sucrose and levulose, or fruit 
sugar. Like the potato, carrots have some organic 
acids and a relatively small amount of proteids. In 
carrots and milk there is practically the same per cent 
of water. The nutrients in each, however, differ both 
as to kind and proportion. Experiments with the 
cooking of carrots show that if a large amount of 
water is used, 30 per cent or more of the nutri- 
ents, particularly of the more soluble sugar and albu- 
min, are extracted and lost in the drain waters. ^^ The 
color of the carrot is due to the non-nitrogenous com- 
pound carrotin, CggHgg. Carrots are valuable in a 
ration not because of the nutrients they supply, but for 
the palatability and the mechanical action which the 
vegetable fiber exerts upon the process of digestion. 

38, Parsnips contain more solid matter than beets or 
carrots, of which 3 to 4 per cent is starch. The starch 
grains are very small, being only about one twentieth 
the size of the potato starch grains. There is 3 per cent 
of sugar and an appreciable amount of fat, more than 
in any other of the vegetables of this class, and seven 
times as much as in the potato. The mineral matter is 
of somewhat different nature from that in potatoes ; in 
parsnips one half is potash and one quarter phosphoric 



VEGETABLE FOODS 



41 



acid, while in potatoes three quarters are potash and 
one fifth phosphoric acid. 

39. Cabbage contains very little dry matter, usually 
less than 10 per cent. It is proportionally richer in 
nitrogenous com- 
pounds than many 
vegetables, as about 
two of the ten parts 
of dry matter are 
crude protein, which 
makes the nutritive 
ratio one to five. 
During cooking 30 
to 40 per cent of 
the nutrients are 
extracted. Cabbage 
imparts to the ration 
bulk but compara- 
tively little nutritive material. It is a valuable food 
adjunct, particularly used raw, as in a salad, when it is 
easily digested and retains all of the nutrients. ^^ 

40. Cauliflower has much the same general composi- 
tion as cabbage, from which it differs mainly in mechan- 
ical structure. 




F(G. 10. —Graphic Composition of 
Cabbage. 



41. Beets. — The garden beet contains a little more 
protein than carrots, but otherwise has about the same 
general composition, and the statements made in regard 



42 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

to the losses of nutrients in the cooking of carrots and 
to their use in the dietary apply also to beets. 

42. Cucumbers contain about 4 per cent of dry 
matter. The amount of nutrients is so small as to 
scarcely allow them to be considered a food. They are, 
however, a valuable food adjunct, as they impart palata- 
bility. 

43. Lettuce contains about 7 per cent of solids, of 
which 1.5 is protein and 2.5 starch and sugar. While 
low in nutrients, it is high in dietetic value, because of 
the chlorophyll which it contains. It has been suggested 
that it is valuable, too, for supplying iron in an organic 
form, as there is iron chemically combined with the 
chlorophyll. 

44. Onions are aromatic bulbs, valuable for condi- 
mental rather than nutritive purposes. They contain 
essential and volatile oils, which impart characteristic 
odor and flavor. In the onion there are about 1.5 per 
cent of protein and 9.5 per cent of non-nitrogenous 
material. Onions are often useful in stimulating the 
digestive tract to action. 

45. Spinach is a valuable food, not to be classed 
merely as a relish. Its composition is interesting ; for, 
although there is 90 per cent water, and less than 10 
per cent dry matter, it still possesses high food value. 
Spinach contains 2. i per cent crude protein, or about one 
part to every four parts of carbohydrates. In potatoes, 



VEGETABLE FOODS 



43 



turnips, and beets there are ten or more parts of car- 
bohydrates to every one part of protein. 

46. Asparagus is composed largely of water, about 
93 per cent. The dry matter, however, is richer in pro- 
tein than that of many vegetables. Asparagus contains, 
too, an amid compound, asparagin, which gives some of 
the characteristics to the vegetable. 

47. Melons. — Melons contain from 8 to lo per cent 
of dry matter, the larger portion of which is sugar and 
allied carbohydrates. The flavor is due to small amounts 
of essential, oils and to organic acids associated with 
the sugars. Melons possess condimental rather than 
nutritive value. 



48. Tomatoes. — The tomato belongs to the night- 
shade family, and for this reason was long looked upon 

with suspicion. It was 
first used for ornamental 
purposes and was called 
" love-apple." Gradu- 
ally, as the idea of its 
poisonous nature be- 
came dis- 

non-sugar solids ■,-, ^ ., 

pelled. It 
grew more and more 
popular as a food, until 
now in the United States 

it is one of the most common garden vegetables. 

It contains / per cent of dry matter, 4 per cent of 




Fig. II. 



Graphic Composition of 
Tomato. 



44 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

which is sucrose, dextrose, and levulose. It also con- 
tains some malic acid, and a small amount of pro- 
teids, amids, cellulose, and coloring material. In the 
canning of tomatoes, if too much of the juice is excluded, 
a large part of the nutritive material is lost, as the sugars 
and albumins are all soluble and readily removed. ^^ If 
the seeds are objectionable, they may be removed by 
straining and the juice added to the fleshy portion. The 
product then has a higher nutritive value than if the 
juice had been discarded with the seeds. 

49. Sweet Corn. — Fresh, soft, green, sweet corn con- 
tains about 75 per cent of water. The dry matter is 
half starch and one quarter sugar. The protein content 
makes up nearly 5 per cent, a larger proportional amount 
than is found in the ripened corn, due to the fact that 
the proteids are deposited in the early stages of growth 
and the carbohydrates mainly in the last stages. Sweet 
corn is a vegetable of high nutritive value and palata- 
bility. 

50. Eggplant contains a high per cent of water, — 90 
per cent. The principal nutrients are starch and sugar, 
which make up about half the weight of the dry matter. 
It does not itself supp'ly a large amount of nutrients, 
but the way in which it is prepared, by combination with 
butter, bread crumbs, and eggs, makes it a nutritious and 
palatable dish, the food value being derived mainly from 
the materials with which it is combined, the eggplant 
giving the flavor and palatability. 



VEGETABLE FOODS 45 

51. Squash and Pumpkin. — Squash has much the 
same general composition and food value as beets and 
carrots, although it belongs to a different family. Pump- 
kins contain less dry matter than squash. The dry mat- 
ter of both is composed largely of starch and sugar and, 
like many other of the vegetables, they are often com- 
bined with food materials containing a large amount of 
nutrients, as in pumpkin and squash pies, where the food 
value is derived mainly from the milk, sugar, eggs, flour, 
and butter or other shortening used. 

52. Celery. — The dry matter of celery is compar- 
atively rich in nitrogenous material, although the 
amount is small, and the larger proportion is in non- 
proteid form. When grown on rich soil, celery -may 
contain an appreciable quantity of nitrates and nitrites, 
which have not been converted into amids and proteids. 
The supposed medicinal value is probably due to the 
nitrites which are generally present. Celery is valuable 
from a dietetic rather than a nutritive point of view. 

53. Sanitary Condition of Vegetables. — The conditions 
under which vegetables are grown have much to do with 
their value, particularly from a sanitary point of view. 
Uncooked vegetables often cause the spread of diseases, 
particularly those, as cholera and typhoid, affecting the 
digestive tract. Particles of dirt containing the disease- 
producing organisms adhere to the uncooked vegetable 
and find their way into the digestive tract, where the bac- 
teria undergo incubation. When sewage has been used 



46 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

for fertilizing the land, as in sewage irrigation, the vege- 
tables are unsound from a sanitary point of view. Such 
vegetables should be thoroughly cleaned and also well 
cooked, in order to render them sterile. Vegetables to 
be eaten in the raw state should be dipped momentarily 
into boiling water, to destroy the activity of the germs 
present upon the surface. They may then be immedi- 
ately immersed in ice-cold water, to preserve the crisp- 
ness. 

54. Miscellaneous Compounds in Vegetables. — In ad- 
dition to the general nutrients which have been discussed, 
many of the vegetables contain some tannin, glucosides, 
and essential oils ; and occasionally those grown upon 
rich soils have appreciable amounts of nitrogen com- 
pounds, as nitrates and nitrites, which have not been 
built up into proteids. Vegetables have a unique value 
in the dietary, and while as a class they contain small 
amounts of nutrients, they are indispensable for promot- 
ing health and securing normal digestion of the food. 

55. Canned Vegetables. — When sound vegetables are 
thoroughly cooked to destroy ferments, and then sealed 
in cans while hot, they can be kept for a long time 
without any material impairment of nutritive value. 
During the cooking process there is lost a part of the 
essential oils, which gives a slightly different flavor to 
the canned or tinned goods. ^^ In some canned vege- 
tables preservatives are used, but the enactment and 
enforcement of national and state laws have greatly 



VEGETABLE FOODS 47 

reduced their use. When the cans are made of a poor 
quality of tin, or the vegetables are of high acidity, 
some of the metal is dissolved in sufficient quantity to 
be objectionable from a sanitary point of view.^^ 

56. Edible Portion and Refuse of Vegetables. — Many 
vegetables have appreciable amounts of refuse,^^ or 
non-edible parts, as skin, pods, seeds, and pulp, and in 
determining the nutritive value, these must be consid- 
ered, as in some cases less than 50 per cent of the 
weight of the material is edible portion, which propor- 
tionally increases the cost of the nutrients. Ordinarily, 
the edible part is richer in protein than the entire 
material as purchased. In some cases, however, the 
refuse is richer in protein, but the protein is in a less 
available form. See comparison of potatoes and potato 
skins. 



CHAPTER IV 

FRUITS, FLAVORS, AND EXTRACTS 

57. General Composition. — Fruits are characterized 
by containing a large amount of water and only a small 
amount of dry matter, which is composed mainly of 
sugar and non-nitrogenous compounds. Fruits contain 
but little fatty material and protein. A large portion 
of the total nitrogen is in the form of amid compounds. 
Organic acids, as citric, tartaric, and malic, are found 
in all fruits, and the essential oils form a characteristic 
feature. The taste of fruits is due mainly to the blend- 
ing of the various organic acids, essential oils, and 
sugars. Although fruits contain a high per cent of 
water, they are nevertheless valuable as food.^^ The 
constituents present to the greatest extent are sugars 
and acids. The sugar is not all like the common granu- 
lated sugar, but in ripe fruits a part is in the form 
known as levulose or fruit sugar, which is two and a 
half times sweeter than granulated sugar. Sugars are 
valuable for heat- and fat-producing purposes, but not 
for muscle repairing. Proteids are the muscle-forming 
nutrients. The organic acids, as malic acid in apples, 
citric acid in lemons and oranges, and tartaric acid in 
grapes, have characteristic medicinal properties. The 

48 



FRUITS, FLAVORS, AND EXTRACTS 



49 



sugar, proteid, and acid content of some of our more 
common fruits is given in the following table :'^^ 





Composition of 


Fruits 








Water 


Proteids 


Sugar 


Acid in 
Juice 


Kind of 
Acid 




Per Cent 


Per Cent 


Per Cent 


Per Cent 




Apples (Baldwin) 


85.0 


0.50 


10.75 


0.92 


Malic 


Apples, sweet . . 


86.0 


0.50 


11.75 


0.20 


iMalic 


Blackberries . . 


88.9 


0.90 


I 1.50 


0.75 


Malic 


Currants .... 


86.0 


— 


1.96 


5.80 


Tartaric 


Grapes .... 


83.0 


1.50 


10 to 16 


1.2 to 5 


Tartaric 


Strawberries . . 


90.8 


0.95 


536 


1.40 


Malic 


Oranges .... 


85.0 


1. 10 


1000 


I -30 


Citric 


Lemons .... 


84.0 


0.95 


2.00 


7.20 


Citric 



In addition to sugars, acids, and proteids, there are a 
great many other compounds in fruits. Those which 
give the characteristic taste are called essential or vola- 
tile oils. 

58. Food Value. — When the nutrients alone are con- 
sidered, fruits appear to have a low food value, but they 
should not be judged entirely on this basis, because 
they impart palatability and flavor to other foods and 
exercise a favorable influence upon the digestive process. 
In the human ration fruits are a necessary adjunct. 

59. Apples. — Apples vary in composition with the 
variety and physical characteristics of the fruit. In 
general they contain from 10 to 16 per cent of dry mat- 
ter, of which 75 per cent, or more, is sugar or allied 



50 



liUiMAN FOODS AND THEIR NUTRITIVE VALUE 




Fig. 12. — Graphic Composition 
OF Apple. 



carbohydrates. Among the 
organic acids malic pre- 
dominates, and the acidity 
ranges from o.i to 0.8 per 
cent. Apples contain but 
Httle protein, less than i 
per cent. There is some 
pectin, or jelly-like sub- 
stance closely related to 
the carbohydrates. The 
flavor of the apple varies 
with the content of sugar, 
organic acids, and essen- 
tial oils. During storage some apples appear to undergo 
further ripening, resulting in partial inversion of the 
sucrose, and there is a 
slight loss of weight, 
due to the formation of 
carbon dioxid. The 
apple is an important 
and valuable adjunct 
to the dietary.^ 



60. Oranges contain 
nearly the same pro- 
portion of dry matter 
as apples, the larger 
part of which is sugar. 
Citric acid predomi- 




FlG. 13. 



Graphic Composition of 
Orange. 



FRUITS, FLAVORS, AND EXTRACTS 



51 



nates and ranges in different varieties from i to 2.5 per 
cent. The amounts of protein, fat, and cellulose are 
small. In some varieties of oranges there is more iron 
and sulphur than is usually found in fruits. All fruits, 
however, contain small amounts, but not as much as is 
found in green vegetables. The average composition 
of oranges is as follows : 



Physical Composition 



Per Cent 

Rind 20 to 30 

Pulp 25 to 35 

Juice 35 to 50 



Chemical CoMPOSinoN of Edible Portion 



Per Cent 

Solids 10 to 16 

Sugars 8 to 1 2 

Citric acid i to 2.5 

Ash 0.5 



61. Lemons differ from oranges in containing more 
citric acid and less sucrose, levulose, and dextrose. The 
ash of the lemon is somewhat similar in general compo- 
sition to the ash of the orange, but is larger in amount. 
The average composition of the lemon is as follows : 



Physical Composition 

Per Cent 

Rind -5 to 35 

Pulp 25 to 35 

Juice 40 to 55 



Chemical Composition of Edible Portion 



Solids . . 
Sugar . . 
Citric acid 



Per Cent 

1.0 to 12 

2 to 4 

6 to 9 



62. Grape Fruit. — The rind and seed of this fruit 
make up about 25 per cent, leaving 75 per cent as 
edible portion. The juice contains 14 percent soHds, of 



52 



HUMAN FOODS AND THEIR NUTRITIVE VALUE 



which nearly lO per cent is sugar and 2.5 per cent is 
citric acid. There is more acid in grape fruit than in 
oranges and appreciably less than in lemons. The 
characteristic flavor is due to a glucoside-like material. 
Otherwise the composition and food value are about the 
same as of oranges. 



63. Strawberries contain from 8 to 12 per cent of 
dry matter, mainly sugar and malic acid. The pro- 
tein, fat, and ash usually 
make up less than 2. per 
cent. Essential oils and 
coloring substances are 
present in small amounts. 
It has been estimated that 
it would require 75 pounds 
of strawberries to supply 
the protein for a daily ra- 
tion. Nevertheless they 
are valuable in the die- 
tary. It has been sug- 
gested that the malic and 
other acids have antisep- 
tic properties which, add- 
ed to the appearance and 
palatability, make them a 
desirable food adjunct. 
Strawberries have high dietetic rather than high food 
value. 




Fig. 14.— Graphic Composition 
OF Strawberry. 



FRUITS, FLAVORS, AND EXTRACTS 53 

64. Grapes contain more dry matter than apples or 
oranges. There is no appreciable amount of protein or 
fat, and while they add some nutrients, as sugar, to the 
ration, they do not contribute any quantity. Their 
value, as in the case of other fruits, is due to palatability 
and indirect effect upon the digestibility of other foods. 
In the juice of grapes there is from lo to 15 per cent or 
more of sugar, as sucrose, levulose, and dextrose. Grapes 
contain also from i to 1.5 per cent of tartaric acid, 
which, during the process of manufacture into wine, is 
rendered insoluble by the alcohol formed, and the 
product, known as argole, is used in the preparation 
of cream of tartar. Differences in flavor and taste 
of grapes are due to variations in the sugar, acid, 
and essential oil content. 

65. Peaches contain about 12 per cent of dry matter, 
of which over 10 per cent is sugar and other carbohy- 
drates. There is less than 1.5 percent of protein, fat, 
and mineral matter and about 0.5 percent of acid. The 
peach contains also a very small amount of hydrocyanic 
acid, which is more liberally present in the kernel than 
in the fruit. Flavor is imparted mainly by the sugar 
and essential oils. Peaches vary in composition with 
variety and environment.^^ 

66. Plums contain the most dry matter of any of the 
fruits, about 22 per cent, mainly sugar. About one 
per cent is acid and about 0.5 per cent are protein and 
ash. There are a great many varieties of plums, vary- 



54 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

ing in composition. Dried plums (prunes) have mildly 
laxative properties. 

67. Olives. — The ripe olive contains about 15 per 
cent of oil, exclusive of the pit, which makes up 20 per 
cent of the weight. In green, preserved olives there is 
considerably less oil. Because of the oil the olive has 
food value. Olive oil is slightly laxative and assists 
mechanically in the digestion of foods. 

68. Figs. — Dried figs contain about 50 per cent of 
sugar and 3.5 per cent of protein. The fig has a mildly 
laxative action. 

69. Dried Fruits. — Many fruits are prepared for 
market by drying. The dried fruit has a slightly 
different composition from the fresh fruit because of 
loss of the volatile and essential oils, and minor chemical 
changes which take place during the drying process. 
When free from preservatives, dried fruits are valuable 
adjuncts to the dietary and can be advantageously used 
when fresh fruits are not obtainable. 

70. Canning and Preservation of Fruits. — To obtain 
the best results in canning, the fruit should not be over- 
ripe. After the ripened state has been reached fermen- 
tation and bacterial changes occur, and it is more difficult 
to preserve the fruit than when not so fully matured. 2* 
When a fruit has begun to ferment, it is hard to destroy 
the ferment bodies and their spores so as to prevent 
further ferment action. The chemical changes that oc- 



FRUITS, FLAVORS, AND EXTRACTS 55 

cur ill the last stages of ripening are similar to those 
which take place during the cooking process whereby 
the pectin or jelly-like substances are rendered more 
soluble and digestible. 

71. Adulterated Canned Fruits. — Analyses of a num- 
ber of canned fruits, made by various Boards of Health, 
show the presence of small amounts of arsenic, tin, 
lead, and other poisonous metals. The quantity dis- 
solved, depends upon the kind, age, and condition of the 
canned goods and the state of the fruit when canned. 
The longer a can of fruit or vegetable has been kept in 
stock, the larger is the amount of tin or metal that has 
been dissolved. When fresh canned, there is usually 
very' little dissolved tin, but in old goods the amount 
may be comparatively large. The tin used for the can 
is occasionally of poor quality and may contain some 
arsenic, which also is dissolved. The occasional use of 
canned goods preserved in tin is not objectionable, but 
they should not be used continually if it can be avoided. 
Preservatives, as borax, salicylic acid, benzoic acid, and 
sodium sulphate, are sometimes added to prevent fer- 
mentation and to preserve the natural appearance of 
the fruit or vegetable. ^^ 

72. Fruit Flavors and Extracts. — Formerly all fruit 
extracts and flavors were obtained from vegetable 
sources ; at present many are made in the chemical 
laboratory by synthetic methods ; that is, by combining 
simpler organic compounds and radicals to produce the 



56 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

material having the desired flavor and odor. The vari- 
ous fruit flavors are definite chemical compounds, and 
can be produced in the laboratory as well as in the cells 
of plants. When properly made, there is no difference 
in chemical composition between the two. As prepared 
in the laboratory, however, traces of acids, alkahes, and 
other compounds, used in bringing about the necessary 
chemical combination, are often present, not having been 
perfectly removed. Hence it is that natural and artifi- 
cial flavors differ mainly in the impurities which the 
artificial flavors may contain. 

Some of the flavoring materials have characteristic 
medicinal properties, as the flavor of bitter almond, 
which contains hydrocyanic acid, a poisonous substance. 
Flavors and extracts should not be indiscriminately used. 
In small amounts they often exert a favorable influence 
upon the digestion of foods, and the value of some fruits 
is in a large measure due to the special flavors they con- 
tain. A study of the separate compounds which impart 
flavor to fruits, as the various aldehydes, ethers, and or- 
ganic salts, belongs to organic chemistry rather than to 
foods. Some of the simpler compounds of which flavors 
are composed may exist in entirely different form or 
combination in food products ; as for example, pineapple 
flavoring is ethyl butrate. This can be prepared by 
combination of butyric acid from stale butter with alcohol 
which supplies the ethyl radical. The chemical union 
of the two produces the new compound, ethyl butrate, 
the distinctive flavoring substance of the pineapple. 



FRUITS, FLAVORS, AND EXTRACTS 57 

Banana flavor can be made from stale butter, caustic soda, 
and chloroform. None of these materials, as such, go into 
the flavor, but an essential radical is taken from each. 
These manufactured products, when properly made, are 
in every essential similar to the flavor made by the plant 
and stored up in the fruit. The plant combines the ma- 
terial in the laboratory of the plant cell, and the manu- 
facturer of essences puts together these same constitu- 
ents in a chemical laboratory. In the fruit, however, 
the essential oil is associated with a number of other 
compounds. 



CHAPTER V 
SUGARS, MOLASSES, SYRUP, HONEY, AND CONFECTIONS 

73. Composition of Sugars. — The term "sugar" is 
applied to a large class of compounds composed of the 
elements carbon, hydrogen, and oxygen. Sugars used 
for household purposes are derived mainly from the 
sugar cane and the sugar beet.^^ At the present time 
about two fifths are obtained from the cane and about 
three fifths from the beet. When subjected to the 
same degree of refining, there is no difference in the 
chemical composition of the sugars from the two 
sources; they are alike in every respect and the chem- 
ist is unable to determine their origin. The production 
of sugar is an agricultural industry; the methods of 
manufacture pertain more to industrial chemistry than 
to the chemistry of foods, and therefore a discussion of 
them is omitted in this work.-*^ 

74. Commercial Grades of Sugar. — Sugars are graded 
according to the size of the granule, the color and 
general appearance of the crystals, and the per cent 
of sucrose or pure sugar. Common granulated sugar 
is from 98.5 to 99.7 per cent pure sucrose. The impuri- 

58 



SUGARS, MOLASSES, SYRUP, HONEY, CONFECTIONS 59 



ties consist mainly of moisture and mineral matter. 
In the process of refining, sulphur fumes are frequently 
used for bleaching and clarifying the solution.^^ . The 
sulphurous acid formed 
is neutralized with Hme, 
which is rendered insol- 
uble and practically all 
removed in subsequent 
filtrations. There are, 
however, traces of sul- 
phates and sulphites in 
ordinary sugar, but these 



% i m 



Fig. 15. — Sugar Crystals. 



are in such small 
amounts as not to be 

injurious to health. When sugar is burned, as in the 
bomb calorimeter, so as to permit collection of all 
of the products of combustion, granulated sugar yields 
about o.oi of a per cent of sulphur dioxid.^^ Occa- 
sionally coloring substances, as a small amount of in- 
digo, are added to yellow tinged sugars to impart 
a white color, much on the same principle as the 
bluing of clothes. The amount used is usually ex- 
tremely small, and the effect on health has never 
been determined. Occasionally, however, bluing is 
used to such an extent that a blue scum appears 
when the sugar is boiled with water. Sugar has high 
value for the production of heat and energy. Diges- 
tion experiments show that when it is used in the die- 
tary in not excessive amounts, it is directly absorbed by 



6o HUxMAN FOODS AND THEIR NUTRITIVE VALUE 

the body and practically all available. It can advan- 
tageously be combined with other foods to form a part 
of the ration.^" When a ration contains the requisite 
amount of protein, sugar is used to the best advantage. 
Alone it is incapable of sustaining life, because it does 
not contain any nitrogen. When sugar was substituted 
for an excess of protein in a ration, it was found to pro- 
duce heat and energy at much less expense. Many 
foods, as apples, grapes, and small fruits, contain appre- 
ciable amounts of sugar and owe their food value al- 
most entirely to their sugar content. In the dietary, 
sugar is too frequently regarded as a condiment instead 
of a nutrient, to be used for imparting palatability 
rather than for purposes of nutrition. While valuable 
for improving the taste of foods, the main worth of 
sugar is as a nutritive substance ; used in the prepara- 
tion of foods it adds to the total heat and energy of the 
ration. Sugar is sometimes used in excessive amounts 
and, as is the case with any food or nutrient, when that 
occurs, nutrition disturbances result, due to misuse of 
the food. Statistics show that the average consump- 
tion of sugar in the United States is nearly 70 pounds a 
year per capita. In the dietary of the adult, sugar to 
the extent of four ounces per day can be consumed 
advantageously. The exclusion of sugar from the diet 
of children is a great mistake, as they need it for heat 
and energy and to conserve the protein for growth. 

" Sugar is one of the most important forms in which carbo- 
hydrates can be added to the diet of children- The great reduction 



SUGARS, MOLASSES, SYRUP, HONEY, CONFECTIONS 6l 

in the price of sugar which has taken place in recent years is 
probably one of the causes of the improved physique of the rising 
generation. The fear that sugar may injure children's teeth is 
largely illusory. The negroes who live largely on sugar cane have 
the finest teeth the world can show. If injudiciously taken, sugar 
may, however, injure the child's appetite and digestion. The crav- 
ing for sweets which children show is no doubt the natural expres- 
sion of a physiological need, but they should be taken with, and not 
between, meals." ^^ 

75. Sugar in the Dietary. — Sugar has an important 
place in the dietary. It not only serves for the produc- 



Proten 



Fdit 



Cdtdokydrdtes 



Fig. i6. — Nutrients of a Ration with Sugar. 

tion of heat and energy in the body, but is also valuable 
in enabling the proteids to be used more economically. 
In reasonable amounts, it is particularly valuable in the 
dietary of growing children, as the proteids of the food 
are then utilized to better advantage for growth. The 
unique value of sugar depends upon its intelHgent use 
and its proper combination with other foods, particularly 
with those rich in the nitrogenous compounds or pro- 
teids. Sugar alone is incapable of sustaining hfe, but 
combined with other foods is a valuable nutrient. The 
amount which can be advantageously used depends 



62 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

largely upon the individual. Ordinarily three to five 
ounces per day is sufificient, although some persons can- 
not safely consume as much as this. In the case of 
diabetes mellitus, the amount of sugar in the ration 
must be materially reduced. Persons in normal health 
and engaged in outdoor work can use sugar to advan- 
tage.^'^ Many of the " harvest drinks, " made largely 
from molasses with a little ginger, and used extensively 
in some localities, are not without merit, as they contain 



protein 



^ 
^ 



F^t 



^1 



Carbohyo^rates 




Fig. 17. — Nutrients of a Ration without Sugar. 

an appreciable amount of nutrients. Milk contains 
more sugar as lactose or milk sugar than any other 
nutrient. 

The craving for sugar by growing children and ath- 
letes is natural. Sugar, however, is often injudiciously 
used, and a perverted taste may be established which 
can be satisfied only by excessive amounts. This re- 
sults in impaired digestion and malnutrition. 

76. Maple Sugar. — Sugar obtained by evaporation 
from the sap of the maple tree (Acer saccJiarinuni) is 



SUGARS, MOLASSES, SYRUP, HONEY, UONFEUTIONS 63 

identical, except for the foreign substances which it 
contains, with that from the beet and sugar cane. The 
mottled appearance and characteristic color and taste of 
maple sugar are due to the various organic acids and 
other compounds present in the maple sap and recovered 
in the sugar. Maple sugar, as ordinarily prepared, has 
0.4 of a per cent or more of ash or mineral matter, while 
refined cane sugar contains less than one tenth as much.^ 
Hence, when maple sugar is adulterated with cane and 
beet sugars, the ash content is noticeably lowered, as is 
also the content of organic acids. It is difficult, how- 
ever, to determine with absolute certainty pure high 
grade maple sugar from the impure low grade to 
which a small amount of granulated sugar has been 
added. 

77. Adulteration of Sugar. — Sugar at the present 
time is not materially adulterated. Other than the 
substances mentioned which are used for clarification 
and color, none are added during refining which remain 
in the sugar in appreciable amounts. Sugar does not 
readily lend itself to adulteration, as it has a definite 
crystalline structure, and materials that would be suit- 
able for its adulteration are of entirely different physical 
character.-^^ Cane sugar is not easily blended with 
glucose, or starch sugar, because of the physical differ- 
ences between the two. The question of the kind of 
sugar to use in the household, as granulated, loaf, or 
pulverized, is largely one of personal choice, as there is 



64 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

no appreciable difference in the nutritive value or purity 
of the different kinds. 

78. Dextrose Sugars. — Products known as glucose and 
dextrose sugars are made from corn and other starches; 
they can also be prepared from cane sugar by the use 
of heat, chemicals, or ferments for carrying on the pro- 
cess known as inversion. The dextrose sugars differ 
from cane sugar in containing a dissimilar number of 
carbon, hydrogen, and oxygen atoms in the molecule. 
The formula of the dextrose sugars is CqH^^^q, while 
that of cane sugar is C12H22O11. By the addition of one 
molecule of water, H2O, to a molecule of sucrose, two 
molecules of invert sugar (dextrose and glucose) are pro- 
duced : 1 C12H22O11 + H2O = C6H12O6 + CqUi^q. In 
bringing about this change, acids are employed, but the 
acid in no way enters into the chemical composition of 
the final product ; it is removed as described during the 
process of sugar manufacture. The action of the acid 
brings about a catalytic change, the acid being necessary 
only as a presence reagent to start the chemical reac- 
tion. When properly prepared and the acid product 
thoroughly removed, dextrose and glucose have practi- 
cally the same food value as sugar. When they are 
digested, heat and energy are produced, and a given 
weight has about the same fuel value as an equal 
weight of sugar. Some of the glucose-yielding products 
can be made at less expense than sugar, and when they 
are sold under their right names there is no reason why 



SUGARS, MOLASSES, SYRUP, HONEY, CONFECTIONS 65 

they should not be used in the dietary, as they serve 
the same nutritive purpose. 

79. Molasses is a by-product obtained in the reiining 
of sugar. It is a mixture of cane sugar and invert 
sugars, as levulose and dextrose. When in sugar 
making the sucrose is removed by crystaUization, a point 
is finally reached where the solution, or mother hquid, 
as it is called, refuses to give up any further crystals ; ^^ 
then this product, consisting of various sugars and 
small amounts of organic acids and ash, is partially re- 
fined and clarified to form molasses. The term " New- 
Orleans " molasses was formerly applied to the product 
obtained by the use of open kettles for the manufacture 
of sugar, but during recent years the vacuum pan pro- 
cess has been introduced, and " New Orleans " molasses 
is now an entirely different article. The terms first, 
second, and third molasses are applied to the liquids 
obtained after the removal of the first, second, and third 
crops of sugar crystals ; first molasses being richer in 
sucrose, while third molasses is richer in dextrose and 
invert sugars. The ash in molasses ranges from 4 to 
6.5 per cent. Some of the low grades of molasses are 
used in the preparation of animal foods. 

The taste and physical characteristics of molasses are 
due largely to the organic acids and impurities that are 
present, as well as to the proportion in which the vari- 
ous sugars occur. When used with soda in cooking and 
baking operations, the organic acid of the molasses lib- 



66 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

erates carbon dioxid gas, which acts as a leavening 
agent. Because of the organic acids, molasses should 
not be stored in tin or metalware dishes, as the solvent 
action results in producing poisonous tin and other 
metallic salts. 

The food value of molasses is dependent entirely upon 
the amount of dry matter and the per cent of sugar. 
A large amount of water is considered an adulterant ; 
ordinarily molasses contains from 20 to 33 per cent. 
If a sample of molasses contains 75 per cent of dry mat- 
ter, it has slightly less than three fourths of the nutritive 
value of the same weight of sugar. 

80. Syrups. — The term ''syrup " is applied to natu- 
ral products obtained by evaporation and purification of 
the saccharine juices of plants. Sorghum syrup is from 
the sorghum plant, which is pressed by machinery and 
the juice clarified and evaporated so as to contain about 
25 per cent of water. In sorghum syrups there are from 
30 to 45 per cent of cane sugar, and from 12 to 20 per 
cent of glucose and invert sugars. Cane syrup is made 
from the clarified juice of the sugar cane, and has about 
the same general composition as sorghum syrup. Maple 
syrup, prepared from the juice of the sugar maple, is 
characteristically rich in sucrose and contains but little 
glucose or reducing sugars. The flavor of all the 
syrups is due mainly to organic acids, ethereal prod- 
ucts, and impurities. In some instances the essential 
flavor can be produced synthetically, or derived from 



SUGARS, MOLASSES, SYRUP, HONEY, CONFECTIONS 67 



Other and cheaper materials ; and by the use of these 
flavors, mixed syrups can be prepared closely resem- 
bUng many of the natural products. When properly 
made, they are equal in nutritive value to natural syr- 
ups. When sold under assumed names, they are to be 
considered and classified as 
adulterated, and not as syr- 
ups from definite and spe- 
cific products. Low-grade 
syrups and molasses are 
often used for making fuel 
alcohol. They readily un- 
dergo alcoholic fermentation 
and are valuable for this 
purpose, rendering it pos- 
sible for a good grade of 
fuel alcohol to be produced 
at low cost. The manufac- 
ture 'of sugar, syrups, and 
molasses has been brought 
to a high degree of perfec- 
tion through the assistance 
rendered by industrial chemistry. Losses in the proc- 
ess are reduced to a minimum, and the various steps 
are all controlled by chemical analysis. Sugar has 
the physical property of deflecting a ray of polar- 
ized light, the amount of deflection depending upon 
the quantity of sugar in solution. This is measured 
by the polariscope, an instrument by means of which 




Fig. 



Graphic Composition 
OF Syrup. 



68 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

the sugar content of sugar plants is rapidly deter- 
mined. 

81. Honey is composed largely of invert sugars gath- 
ered by the honeybee from the nectar of flowers. It 
varies in composition and flavor according to its source. 
The color depends upon the flower from which it came, 
white clover giving a light-colored, pleasant-flavored 
honey, while that from buckwheat and goldenrod is 
dark and has a slightly rank taste. The comb is com- 
posed largely of wax, which has somewhat the same 
general composition as fat, but contains ethereal instead 
of glycerol bodies. On account of the predominance 
of invert sugars, pure honey has a levulo or left-handed 
rotation when examined by the polariscope. Honey 
contains from 60 to 75 per cent of invert sugars, and 
from 12 to 20 per cent of water, while the ash content 
is small, less than one tenth of one per cent. Strained 
honey is easily adulterated with glucose products. 
Adulteration with cane sugar is readily detected, as 
pure honey contains only a very small amount of 
sucrose. Honey can be made by feeding bees on 
sugar ; the sugar undergoes inversion, with the pro- 
duction of dextrose. Such honey, although not adul- 
terated, is inferior in quality and lacking in natural 
flavor. 18 

82. Confections. — By blending various saccharine 
products, confections are made. Usually sucrose (cane 
and beet sugar) is used as the basis for their prepa- 



SUGARS, MOLASSES, SYRUP, HONEY, CONFECTIONS 69 

ration. Sucrose has definite physical properties, as 
crystalline structure, and forms chemical and mechan- 
ical combinations with acid, alkahne, and other sub- 
stances ; it also unites with water, and when heated 
undergoes changes in structural composition. The 
presence of small amounts of acid substances, or vari- 
ations in the concentration of the sugar solution, 
materially affect the mechanical relation of the sugar 
particles to each other, and their crystallization. Usu- 
ally crystallization takes place when there is less than 
25 per cent of water present. The form, size, and 
arrangement of the crystals are influenced by agitation 
during cooHng. To secure desired results, often small 
quantities of various other substances are employed for 
their mechanical action. Glucose is frequently used, 
and is said to be necessary for the production of some 
kinds of candy. 

Candies are colored with various dyes and pigments, 
many of which are harmless, although some are in- 
jurious. Coal tar dyes are frequently employed for 
this purpose. Objection has generally been urged 
against their use, as it is believed many of them are 
injurious to health. It cannot be said, however, that 
all are poisonous, as some are known to be harmless. 
The use of a few coal tar dyes is allowed by the United 
States government. Mineral colors are now rarely, 
if ever, used. 

Impure candies result from objectionable ingredients, 
as starch, paraffin, and large amounts of injurious color- 



70 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

ing substances. Coal tar coloring materials are identi- 
fied in the way described in Experiment No. 13. Con- 
fectionery, when properly prepared and unadulterated, 
has the same nutritive value as sugar and the other ingre- 
dients, and is entitled to a place in the dietary for the 
production of heat and energy. Much larger amounts 
of candies are sold and consumed during the winter 
than the summer months, suggesting that in cold 
weather candy is most needed in the dietary. 

83. Saccharine is an artificial sweetening, five hun- 
dred times sweeter than cane sugar. It contains in its 
molecule, chemically united, benzine, sulphuric acid, and 
ammonia radicals. It is employed for sweetening pur- 
poses in cases of diabetes mellitus, where physicians 
advise against the use of sugar. It has no food value. 
A small amount is sometimes added to canned corn 
and tomatoes to impart a sweet taste. The physio- 
logical properties of saccharine have not been exten- 
sively investigated. 



CHAPTER VI 
LEGUMES AND NUTS 

84. General Composition of Legumes. — Peas, beans, 
lentils, and peanuts are the legumes most generally used 
for human food. As a class, they are characterized by 
high protein content and a comparatively low per cent 
of starch and carbohydrates. They contain the largest 
amount of nitrogenous compounds of any of the vege- 
table foods, and hence are particularly valuable in the 
human ration as a substitute for meats. ^^ For feeding 
animals the legumes are highly prized, particularly the 
forage crops, clover and alfalfa. These secure their nitro- 
gen, which is the characteristic element of protein, from 
the free nitrogen of the air, through the workings of 
bacterial organisms found in the nodules on the roots 
of the plants. The legumes appear to be the only plants 
capable of making use of the nitrogen of the air for 
food purposes. 

85. Beans contain about 24 per cent of protein and 
but little fat, less than is found in any of the grain or 
cereal products. The protein of the bean differs from 
that of cereals in its general and structural composition. 
It is a globulin known as legumin, and is acted upon 

71 



72 HUMAN FOODS AND THEIR NUTRITIVE VALUE 




mainly by ferments working in alkaline solutions, as in 
the lower part of the digestive tract. Beans have about 

the same amount of ash as the 
cereals, but the ash is richer in 
potash and lime. 

86. Digestibility of Beans. — 

Beans are usually considered 

indigestible, but experiments 

show they are quite completely 

digested, although they require 

more work on the part of the 

digestive tract than many other 

foods. The digestibility was 

FIG. 19. -GRAPHIC CoMPosi- found to vary with individuals, 

TioN OF Beans. Hacked 35 ^qj. ^ent of the protein being 

Part Indigestible. ,. , . , . 

digested in one case, and only 

72 per cent in another. The protein of beans is not 
as completely digested as that of meats. When beans 
were combined with other foods, forming a part of 
a ration, they were more completely digested than 
when used in large amounts and with only a few other 
foods. The presence of the skin is in part responsible 
for low digestibility. When in the preparation of beans 
the skins, which contain a large amount of cellulose, are 
removed, the beans are more completely digested. By 
cooking from twenty minutes to half an hour in rapidly 
boiling water containing a small amount of soda, the 
skins are softened and loosened and are then easily re- 



LEGUMES AND NUTS 



73 



moved by rubbing in cold water. Some of the soda en- 
ters into combination with the legumin. Along with the 
skins a portion of the germ is lost. The germ readily fer- 
ments, which is probably the cause of beans producing 
flatulence with some individuals during digestion. After 
the skins are removed the nutrients are more susceptible 




Fig. 20. — Beans, Raw and Cooked, Skins, Wet and Dry. 

to the action of the digestive fluids. Experiments show 
that 42 per cent of the protein of baked skinned beans 
is soluble in pepsin and pancreatin solutions, while 
under similar conditions there is only 3.85 per cent of 
the protein soluble from beans baked without removal 
of the skins. 



87. Use of Beans in the Dietary. — There is no veg- 
etable food capable of furnishing so much protein at 



74 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

such low cost as beans; from a pound costing five cents 
about one fifth of a pound of protein and three fifths of 
a pound of carbohydrates are obtained. Beans can, to 
a great extent, take the place of meats in the dietary. 
There is more protein in beans than in beef. Four 
ounces of uncooked beans or six ounces of baked beans 
are as much as can conveniently be combined in the 
dietary, and these will furnish a quarter of the protein of 
the ration. In the case of active out-of-door laborers 
over a pound of baked beans per day is often consumed 
with impunity. 

88. String Beans. — String beans — green beans with 
pod — contain a large amount of water, 85 to 8S per 
cent. The dry matter is rich in protein, nearly 20 per 
cent, although in the green beans as eaten, containing 
85 per cent water, there is less than 2.} per cent. Lima 
beans are richer in protein than string beans, as the 
green pod is not included. String beans are valuable 
both for the nutrients they contain and for the favorable 
influence they exert upon the digestibihty of other foods. 

89. Peas. — In general composition and digestibility, 
peas are quite similar to beans. They belong to the 
same family, Leguminosae, and the protein of each is 
similar in quantity and general properties. The state- 
ments made in regard to the composition, digestibility, 
and use of beans in the dietary apply with minor modi- 
fications to peas. When used in the preparation of 
soups, they add appreciable amounts of nutrients. 



LEGUMES AND NUTS 75 



fT'-wm ,r.y ;^ ^ 



•-■' 




s>'' 


V 




4 


vi 





.^■' 



■■•^- 



FiG. 21.— Pea Starch Granules. 

90. Canned Peas. — In order to impart a rich green 
color, copper sulphate has been used in the canning of 
peas. Physiologists differ as to its effect upon health. 
While a little may not be particularly injurious, much 
interferes with normal digestion of the food and forms 
insoluble copper proteids. In some countries a small 



76 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

amount of copper sulphate is tolerated, while in others 
it is prohibited. 

91. Peanuts. — Peanuts differ from peas and beans in 
containing more fat. They should be considered a food, 
for at ordinary prices they furnish a large amount of 
protein and fat. Like the other members of the legume 
family, the peanut is rather slow of digestion and requires 
considerable intestinal work for completion of the process. 

NUTS 

92. General Composition. — Nuts should be regarded 
as food, for they contribute to a ration appreciable 
amounts of nutrients. The edible portion of nearly all 
is rich in fat ; pecans, for example, contain as high as 
70 per cent. In protein content nuts range from 3 per 
cent in cocoanuts to 30 per cent in peanuts. The car- 
bohydrate content is usually comparatively low, less than 
5 per cent in hickory nuts, although there is nearly 40 
per cent in chestnuts. On account of high fat content, 
nuts supply a large amount of heat and energy. ^^ 

93. Chestnuts are characterized by containing less fat 
and protein and much more carbohydrate material, espe- 
cially starch, than is found in other nuts. In southern 
Europe chestnuts are widely used as food ; the skins are 
removed, and the nuts are steamed, boiled, or roasted, 
and sometimes they are dried and ground into flour. 
Chestnuts are less concentrated in protein and fat, and 



LEGUMES AND NUTS 77 

form a better balanced food used alone than do other 
nuts. 

94. The Hickory Nut, which is a characteristically 
American nut, contains in the edible portion about 1 5 
per cent protein, 65 per cent fat, and 12 per cent car- 
bohydrates. 

95. The Almonds used in the United States come 
chiefly from southern Europe, although they are suc- 
cessfully raised in California. They contain about 55 
per cent fat and 22 per cent protein. The flavor of 
almonds is due to a small amount of hydrocyanic acid. 

96. Pistachio. — Some nuts are used for imparting 
color and flavor to food products, as the pistachio nut, 
the kernel of which is greenish in color and imparts a 
flavor suggestive of almonds. The pistachio has high 
food value, as it is rich in both fat and protein. It is 
employed in the manufacture of confectionery and in 
ice cream for imparting flavor and color. 

97. Cocoanuts grow luxuriantly in many tropical coun- 
tries, and have a high food value. They are character- 
istically rich in fat, one half of the edible portion being 
composed of this nutrient. For tropical countries they 
supply the fat of a ration at less expense than any other 
food. When used in large amounts they should be sup- 
plemented with foods rich in carbohydrates, as rice, and 
in proteids, as beans. Cocoanut milk is proportionally 
richer in carbohydrates and poorer in fat and protein 



78 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

than the meat of the cocoanut. In discussing the co- 
coanut, Woods states : ^^ 

'• The small, green, and immature nuts are grated fine for medici- 
nal use, and when mixed with the oil of the ripe nut it be- 
comes a healing ointment. The jelly which lines the shell of the 
more mature nut furnishes a delicate arid nutritious food. The 
milk in its center, when iced, is a most delicious luxury. Grated 
cocoanut forms a part of the world-renowned East India condiment, 
curry. Dried, shredded (desiccated) cocoanut is an important 
article of commerce. From the oil a butter is made, of a clear, 
whitish color, so rich in fat, that of water and foreign substances 
combined there are but 0.0068. It is better adapted for cooking than 
for table use. At present it is chiefly used in hospitals, but it is 
rapidly finding its way to the tables of the poor, particularly as a 
substitute for oleomargarine.'' 

98. Use of Nuts in the Dietary. — When nuts can be 
secured at a low price per pound, ten cents or less, they 
compare favorably in nutritive value with other staple 
foods. Digestion experiments with rations composed 
largely of nuts show that they are quite thoroughly 
digested. Professor Jaffa of the California Experiment 
Station, in discussing the nutritive value of nuts and 
fruits, says : ^ 

" It is certainly an error to consider nuts merely as an accessory 
to an already heavy meal, and to regard fruit merely as something 
of value for its pleasant flavor, or for its hygienic or medicinal virtues. 
The agreement of one food or another with any person is more or 
less a personal idiosyncrasy, but it seems fair to say that those with 
whom nuts and fruits agree, can, if they desire, readily secure a con- 
siderable part of their nutritive material from such sources." 



LEGUMES AND NUTS 



79 



Average Composition of Nuts 

(From Fifteenth Annual Report, Maine Agricultural Experiment Station.) 





Refuse 


Edible 


Edible Portion 






Portion 


Water 


Prot. 


Fat 


Carb. 


Ash 


Value* 
PER Lb. 




% 


% 


% 


% 


% 


% 


% 


Calories 


Almonds . . . . 


64.8 


35-2 


1-7 


7-3 


19-3 


6.2 


0.7 


1065 


Almonds, kernels 


— 


lOO.O 


4.8 


21.0 


549 


17-3 


2.0 


3030 


Brazil nuts .... 


49.6 


50.4 


2.7 


8.6 


33.6 


3-5 


2.0 


1545 


Filberts . . . 




52.1 


47-9 


1.8 


7-5 


31-3 


6.2 


I.I 


1575 


Filberts, kernels 




— 


100. 


3-7 


15.665.3 


13.0 


2.4 


3290 


Hickory nuts . 




62.2 


37-8 


1.4 


5.825.5 


4-3 


0.8 


1265 


Pecans . . . 




49-7 


503 


1.4 


5.235.6 


7.2 


08 


1733 


Pecans, kernels 




— 


1 00.0 


2.9 


10.3 70.8 


14.3 


1-7 


3445 


Walnuts . . . 




58.0 


42.0 


1.2 


7.027.0 


6.1 


0.7 


1385 


Walnuts, kernels 




— 


lOO.O 


2.8 


16.7 


644 


14.8 


1-3 


3305 


Chestnuts . . 




16.1 


83-9 


31.0 


5-7 


6.7 


390 


1-5 


1115 


Acorns . . . 




356 


644 


2.6 


5.2 


24.1 


30-9 


1.6 


1690 


Beechnuts . . 




40.8 


59.2 


2-3 


130 


34-0 


7.8 


2.1 


1820 


Butternuts . . 




86.4 


13.6 


0.6 


3-8 


8.3 


0.5 


0.4 


430 


Litchi nuts . . 




41.6 


58.4 


10.5 


1-7 


0.1 


45.2 


0.9 


875 


Pifion, P. edulis 




40.6 


59-4 


2.0 


8.7 


36.8 


10.2 


1-7 


1905 


Piiion, P. inonopJiyllc 


I 41.7 


58.3 


2.2 


3.8 


354 


15-3 


1.6 


1850 


Pinon, P. sabiiiiana . 


77.0 


23.0 


1.2 


6.5 


12.3 


1.9 


I.I 


675 


Pistachio, kernels 


— 


lOO.O 


4.2 


22.6 


54-5 


15.6 


31 


3010 


Peanuts, raw . . . 


26.4 


736 


6.9 


20.6 


307 


13.8 


1.6 


1935 


Peanuts, kernels 




— 


lOO.O 


93 


27.9 


42.0 18.7 


2.1 


2640 


Roasted peanuts 




32.6 


67.4 


I.I 


20.6 


33.1 10.9 


1-7 


1985 


Shelled peanuts 




— 


1000 


1.6 


30-5 


49.2 


16.2 


2.5 


2955 


Peanut butter . . 




— 


— 


2.0 


29-3 


46.6 


17.1 


t5.o 


2830 


Cocoanuts . . 




48.8 


51.2 


7.2 


2.9 


25.9 


H-3 


09 


1415 


Cocoanuts, shredded 


— 


— 


3-5 


63 


57-3 


31-6 


1-3 


3125 


Cocoanut milk . . 


— 


— 


927 


0.4 


1-5 


4.6 


0.8 


97 



* Calculated from analyses. 



t Including salt, 4.1, 



CHAPTER VII 
MILK AND DAIRY PRODUCTS 

99. Importance in the Dietary. — There is no article 
of food which enters so extensively into the dietary as 
milk, and it is one of the few foods which supply all the 
nutrients, — fats, carbohydrates, and proteids.^^ Milk 
alone is capable of sustaining life for comparatively long 
periods, and it is the chief article of food during many 
diseases. An exclusive milk diet for a healthy adult, 
however, would be unsatisfactory ; in the case of young 
children, milk is essential, because the digestive tract 
has not become functionally developed for the digestion 
of other foods. 

It is necessary to consider not only the composition 
and nutritive value of milk, but also its purity or sanitary 
condition. 

100. General Composition. — Average milk contains 
about Sy per cent water and 13 per cent dry matter. 
The dry matter is composed approximately of : 





Per Cent 


Fat 


3-5 


Casein . . . 


3-25 


Albumin ......... 


0.50 


Milk sugar ......... 


0.50 


Ash 


0.75 



80 



MILK AND DAIRY PRODUCTS 



8i 



Fat is the most variable constituent of milk. Occa- 
sionally it is found as low as 2 per cent and as high 
as 6 per cent or more. The poorest and richest milks 
differ mainly in fat content, as the sugar, ash, casein, 




Fig. 22. — Milk Fat Globules. 

and albumin, or "solids of the milk serum," are fairly 
constant in amount and composition. Variations in the 
content of fat are due to differences in feed and in the 
breed and individuahty of the animal. 

101. Digestibility. — Milk is one of the most com- 
pletely digested of foods, about 95 per cent of the pro- 



82 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

tein and fat and 97 per cent of the carbohydrates being 
absorbed and utilized by the body. 

In a mixed ration, the nutrients of milk are practi- 
cally all absorbed. Milk also exerts a favorable influ- 
ence upon the digestibihty of other foods with which it 
is combined. This is doubtless due to the digestive action 
of the special ferments or enzymes which milk contains. 
In milk there is a soluble ferment material or enzyme 
which has the power of peptonizing proteids. It is this 
ferment which carries on the ripening process when 
cheese is cured in cold storage, and it is beheved to be 
this body which promotes digestion of other foods with 
which milk is combined. ^^ 

Milk is not easily digested by some persons. The 
tendency to costiveness caused by a milk diet can be 
largely overcome by the use of salt with the milk, or of 
some solid food, as toast or crackers, to prevent coagu- 
lation and the formation of masses resistant to the di- 
gestive fluids. Barley water and lime water in small 
amounts are also useful for assisting mechanically in the 
digestion of milk. Milk at ordinary prices is one of the 
cheapest foods that can be used. 

102. Sanitary Condition of Milk. — Equally as im- 
portant as composition is the sanitary condition or 
wholesomeness of milk. Milk is a food material which 
readily undergoes fermentation and is a medium for the 
distribution of germ diseases. The conditions under 
which it is produced and the way in which it is han- 



MILK AND DAIRY PRODUCTS 



83 



died determine largely its sanitary value, and are of so 
much importance in relation to public health that during 
recent years city and state boards of health have intro- 




FiG. 23. — Dirt ix a Sample of Unsanitary Milk. 

duced sanitary inspection and examination of milk along 
with the chemical tests for detecting its adulteration. 
Some of the more frequent causes of contaminated and 
unsound milk are: unhealthy animals, poor food and 



S>4 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

water, unsanitary surroundings of the animals, and lack 
of cleanliness and care in the handhng and transporting 
of the milk. Outbreaks of typhoid and scarlet fevers 
and other germ diseases have frequently been traced to 
a contaminated milk supply.^" 

103o Certified Milk. — When milk is produced under 
the most sanitary conditions, the number of bacterial 
bodies per cubic centimeter is materially reduced. In 
order to supply high grade milk containing but few bac- 
teria, special precautions are taken in the care of the 
animals, and in the feeding and milking, and all sources 
of contamination of the milk are ehminated as far as pos- 
sible. Such milk, when sold in sterilized bottles, is 
commonly called " certified milk," indicating that its 
purity is guaranteed by the producer and that the num- 
ber of bacteria per unit does not exceed a certain stand- 
ard, as 8000 per cubic centimeter. Ordinary market 
milk contains upwards of 50, 000. 

104 Pasteurized Milk. — In order to destroy the 
activity of the bacterial organisms, milk is subjected 
to a temperature of 157° F. for ten minutes or longer, 
which process is known as pasteurization. When milk 
is heated to a temperature above 180°, it is sterilized. 
Below 157°, the albumin is not coagulated.. By pasteur- 
izing, milk is much improved from a sanitary point of 
view, and whenever the milk supply is of unknown 
purity, it should be pasteurized.^^ After the milk has 
been thus treated, the same care should be exercised in 



MILK AND DAIRY PRODUCTS 



8s 




false bottom being in the 






keeping it protected to prevent fresh inoculation or con- 
tamination, as though it were unpasteurized milk. For 
family use milk can be pas- 
teurized in small amounts in 
the following way : Before 
receiving the milk, the re- 
ceptacle should be thor- 
oughly cleaned and sterilized 
with boiling water or dry 
heat, as in an oven. The 
milk is loosely covered and 
placed in a pan of water, a 






Fig. 24. — Pasteurizing Milk. 



pan so as to prevent unequal 
heating. The water surrounding the milk is gradually 
heated until a temperature of 159° F. is registered, and 
the milk is kept at this temperature for about ten 
minutes. It is then cooled and placed in the refrigerator. 

105. Tyrotoxicon. — Tyrotoxicon is a chemical com- 
pound produced by a ferment body which finds its way 
into milk when kept in unsanitary surroundings. It 
induces digestion disorders similar to cholera, and when 
present in large amounts, may prove fatal. It some- 
times develops in cream, ice cream, or cheese, but only 
when they have been kept in unclean places or pro- 
duced from infected milk. 

60i. Color of Milk is often taken as a guide to its 
purity and richness in fat. While a yellow tinge is 



86 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

usually characteristic of milks rich in fat, it is not a 
hard and fast rule, for frequently light-colored milks 
are richer in fat than yellow-tinged ones. The coloring 
material is independent of the percentage of fat, and it 
is not always safe to judge the richness of milk on the 
basis of color. 

107. Souring of Milk. — Souring of milk is due to the 
action of the lactic acid organism, which finds its way 
into the milk through particles of dust carried in the 
air or from unclean receptacles which contain the spores 
of the organism. '^^ When milk sours, a small amount of 
sugar is changed to lactic acid which reacts upon the 
casein, converting it from a soluble to an insoluble con- 
dition. When milk is exposed to the air at a temperature 
of from 70° to 90° F., lactic acid fermentation readily takes 
place. At a low temperature the process is checked, 
and at a high temperature the organisms and spores are 
destroyed. In addition to lactic acid ferments, there are 
large numbers of others which develop in milk, chang- 
ing the different compounds of which milk is composed. 
In the processes of butter and cheese making, these 
fermentation changes are controlled so as to develop 
the flavor and secure the best grades of butter and 
cheese. 

108. Use of Preservatives in Milk. — In order to 
check fermentation, boric acid, formalin, and other pre- 
servatives have been proposed. Physiologists object to 
their use because the quantity required to prevent fer- 



MILK AND DAIRY PRODUCTS 87 

mentation is often sufficient to have a medicinal effect. 
Thie tendency is to use excessive amounts, which may- 
interfere with normal digestion of the food. Milk that 
is cared for under the most sanitary conditions has a 
higher dietetic value and is much to be preferred to that 
which has been kept sweet by the use of preservatives. 

109. Condensed Milk is prepared by evaporating milk 
in vacuum pans until it is reduced about one fourth in 
bulk, when it is sealed in cans, and it will then keep 
sweet for a long time. . Occasionally some cane sugar 
is added to the evaporated product. When diluted, 
evaporated milk has much the same composition as 
whole milk. When a can of condensed milk has been 
opened, the same care should be exercised to prevent 
fermentation as if it were fresh milk. 

110. Skim Milk differs in composition from whole 
milk in fat content. When the fat is removed by the 
separator, there is often left less than one tenth of a 
per cent. Skim milk has a much higher nutritive value 
than is generally conceded, and wherever it can be pro- 
cured at a reasonable price it should be used in the 
dietary as a source of protein. 

111. Cream ranges in fat content from 15 to 35 per 
cent. It is generally preferred to whole milk, although 
it is not as well balanced a food, because it is deficient 
in protein. Cream should contain at least 25 per cent 
of fat. 



88 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

112. Buttermilk is the product left after removal of 
the fat from cream by churning. It has about the same 
amount of nutrients as skim milk. The casein is in a 
slightly modified form due to the development of lactic 
acid during the ripening of the cream, and on this 
account buttermilk is more easily digested and assimi- 
lated by many individuals than milk in other forms. 
The development of the acid generally reduces the 
number of species of other than the lactic organisms, 
and these are increased. 

113. Goat's Milk is somewhat richer in sohds than 
cow's milk, containing about one per cent more proteids, 
a little more fat, and less sugar. When used as a sub- 
stitute for human or cow's milk, it generally needs to be 
slightly diluted, depending, however, upon the composi- 
tion of the individual sample. 

114. Koumiss is a fermented beverage made from 
milk by the use of yeast to secure alcoholic fermenta- 
tion. Koumiss contains about one per cent each of 
lactic acid and alcohol, and the casein and other nutri- 
ents are somewhat modified by the fermentation changes. 
Koumiss is generally considered a non-alcoholic beverage 
possessing both food and dietetic value. 

115. Prepared Milks. — Various preparations are made 
to resemble milk in general .composition. These are 
mechanical mixtures of sugar, fats, and proteids. Milk 
sugar, casein, or malted proteids are generally the 



MILK AND DAIRY PRODUCTS O9 

materials employed in their preparation. Often the 
dried and pulverized solids of skim milk are used. 
Many of the prepared milks are deficient in fat. While 
they are not equal to cow's milk, their use is often made 
necessary from force of circumstances. 

116. Human Milk is not as rich in solid matter as 
cow's milk. It contains about the same amount of fat, 
one per cent more sugar, and one per cent less proteids. 
In human milk nearly one half of the protein is in the 
form of albumins, while in cow's milk there is about one 
fifth in this form. The fat globules are much smaller 
than those of cow's milk. In infant feeding it is often 
necessary to modify cow's milk by the addition of 
water, cream, and milk sugar, so as to make it more 
nearly resemble in composition human milk. 

117. Adulteration of Milk. — Milk is not as exten- 
sively adulterated as it was before the passage and en- 
forcement of the numerous state and municipal laws 
regulating its inspection and sale. The most frequent 
forms of adulteration are addition of water and removal 
of cream. These are readily detected from the specific 
gravity and fat content of the milk. The specific 
gravity of milk is determined by means of the lactom- 
eter, an instrument which sinks to a definite point in 
pure milk. In watered milk it sinks to greater depth, 
depending upon the amount of water added. The fat 
content of milk is readily and accurately determined by 
the Babcock test, in which the fat is separated by cen- 




Fig. 25. — Apparatus used in Testing Milk. 

I, pipette ; 2, lactometer ; 3, acid measure ; 4, centrifuge 
5, test bottle. 

90 



MILK AND DAIRY PRODUCTS 9 1 

trifugal action. For the detection of adulterated milk 
the student is referred to Chapter VI, ** Chemistry of 
Dairying," by Snyder. 

BUTTER 

118. Composition. — Butter is made by the churning 
or agitation of cream and is composed mainly of milk 
fats and water, together with smaller amounts of ash, 
salt, casein, milk sugar, and lactic acid. Average 
butter has the following composition : 



Water . 
Ash and salt 
Casein and albumin 
Fat . . . 



Per Cent 
10.5 

2.5 

I.O 
86.0 



When butter contains an abnormal amount of water, 
it is considered adulterated. According to act of Con- 
gress standard butter should not contain over i6 per 
cent of water nor less than 82.5 per cent of fat. 

119. Digestibility of Butter. — Digestion experiments 
show that practically all of the fat, 98 per cent, is di- 
gestible and available for use by the body. Butter is 
valuable only for the production of heat and energy. 
Alone, it is incapable of sustaining life, because it con- 
tains no proteid material. It is usually one of the more 
expensive items of food, but it is generally considered 
quite necessary in a ration.^ It has been suggested 



92 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

that it takes an important part mechanically in the 
digestion of food. 

120. Adulteration of Butter. — In addition to contain- 
ing an excess of water, butter is adulterated in other 
ways. Old, stale butter is occasionally melted, washed, 
salted, and reworked. This product is known as reno- 
vated butter, and has poor keeping quahties. Frequently 
preservatives are added to such butter to delay fermen- 
tation changes. Oleomargarine and butterine are made 
by mixing vegetable and animal fats."*^ Highly colored 
stearin, cotton-seed oil, and lard are the usual materials 
from which oleomargarine is made. It has practically 
the same composition, digestibility, and food value as 
butter. When sold under its true name and not as 
butter, there is no objection, as it is a valuable food and 
supplies heat and energy at less cost than butter. The 
main objection to oleomargarine and butterine is that 
they are sold as butter. ^^ 

The coloring of butter is not generally looked upon 
as adulteration, for butter naturally has a more or 
less yellow tinge. According to an act of Congress, 
butter colors of a non-injurious character are allowed 
to be used. 

CHEESE 

121. General Composition. — Cheese is made by the 
addition of rennet to ripened milk, resulting in coagu- 
lation of the casein, which mechanically combines with 



MILK AND DAIRY PRODUCTS . 93 

the fat. It differs from butter in composition by con- 
taining, in addition to fat, casein and appreciable 
amounts of mineral matter. The composition varies 
with the character of the milk from which the cheese 
was made. Average milk produces cheese containing 
a larger amount of fat than proteids, while cheese from 
skimmed or partially skimmed milk is proportionally 
poorer in fat. Ordinarily there is about 35 per cent of 
water, 33 per cent of fat, and 27 per cent of casein, and 
albumin or milk proteids, the remainder being ash, salt, 
milk sugar, and lactic acid. Cheese is characterized by 
its large percentage of both fat and protein, and has 
high food value. It contains more fat and protein than 
any of the meats ; in fact, there are but few foods which 
have such liberal amounts of these nutrients as cheese. 

The odor and flavor of cheese are due to workings of 
bacteria which result in the production of aromatic com- 
pounds. The purity and condition of the milk, as well 
as the method of manufacture and the kind of ferment 
material used, determine largely the flavor and odor. 
Cheese is generally allowed to undergo a ripening or 
curing process before it is used as food. The changes 
resulting consist mainly in increased solubility of the 
proteids, with the formation of a small amount of amid 
and aromatic compounds.'^ 

122. Digestibility. — Cheese is popularly considered an 
indigestible food, but extended experiments show that 
it is quite completely digested, although in the case of 



94 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

some individuals not easily digested. In general, about 

95 per cent of the fat and 92 per cent and more of the 
protein is digested, depending upon the general com- 
position of the cheese and the digestive capacity of the 
individual. As far as total digestibility is concerned, 
there appears to be but little difference between green 
and well-cured cheese. So far as ease of digestion is 
concerned, it is probable that some difference exists. 
There is also but little difference in digestibility result- 
ing from the way in which milk is made into cheese, the 
nutrients of Roquefort, Swiss, Camembert, and Cheddar 
being about equally digestible. ^^ The differences in odor 
and taste are due to variations in kind and amount of 
bacterial action. When combined with other foods, 
cheese may exercise a beneficial influence upon diges- 
tion in the same way as noted from the use of several 
foods in a ration. No material differences were ob- 
served in digestibility when cheese was used in small 
amounts, as for condimental purposes, or when used in 
large amounts to furnish nutrients. Artificial digestion 
experiments show that cheese is more readily acted upon 
by the pancreatic than by the gastric fluids, suggest- 
ing that cheese undergoes intestinal rather than gastric 
digestion. It is possible this is the reason that cheese 
is slow of digestion in the case of some individuals. 

123. Use in the Dietary. — Cheese should be used in 
the dietary regularly and in reasonable amounts, rather 
than irregularly and then in large amounts. Cheese is 



MILK AND DAIRY PRODUCTS 95 

not a luxury, but ordinarily it is one of the cheapest and 
most nutritious of human foods. A pound of cheese 
costing 15 cents contains about a quarter of a pound of 
protein and a third of a pound of fat ; at the same price, 
beef yields only about half as much fat and less protein. 
Cheese at 18 cents per pound furnishes more available 
nutrients and energy than beef at 12 cents per pound. 
In the dietary of European armies, cheese to a great 
extent takes the place of beef. See Chapter XVI. 

124. Cottage Cheese is made by coagulating milk and 
preparing the curd by mixing with it cream or melted 
butter and salt or sugar as desired. When milk can be 
procured at little cost, cottage cheese is one of the 
cheapest and most valuable foods.^^ 

125. Different Kinds of Cheese. — By the use of dif- 
ferent kinds of ferments and variations in the process 
of manufacture different types or kinds of cheese are 
made, as Roquefort, Swiss, Edam, Stilton, Camembert, 
etc. In the m.anufacture of Roquefort cheese, which is 
made from goats' and ewes' milk, bread is added and 
the cheese is cured in caves, resulting in the formation 
of a green mold which penetrates the cheese mass, and 
produces characteristic odor aad flavor. Stilton is an 
English soft, rich cheese of mild flavor, made from milk 
to which cream is usually added. It is allowed to un- 
dergo an extended process of ripening, often resulting 
in the formation of bluish green threads of fungus. 
Limburger owes its characteristic odor and flavor to the 



96 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

action of special ferment bodies which carry on the 
ripening process. Neufchatel is a soft cheese made 
from sweet milk to which the rennet is added at a high 
temperature. After pressing, it is kneaded and worked, 
and then put into packages and covered with tin foil. 

126. Adulteration of Cheese. — The most common 
forms of adulteration are the manufacture of skim-milk 
cheese by the removal of the fat from the milk, and 
substitution of cheaper and foreign fats, making a prod- 
uct known as filled cheese. When not labeled whole 
milk cheese, or sold as such, there is no objection to 
skim-milk cheese. It has a high food value and is often 
a cheap source of protein. The manufacture of filled 
cheese is now regulated by the national government, 
and all such cheese must pay a special tax and be prop- 
erly labeled. As a result, the amount of filled cheese 
upon the market has very greatly decreased, and cheese 
is now less adulterated than in former years. The na- 
tional dairy law allows the use of coloring matter of a 
harmless nature in the manufacture of cheese. 

127. Dairy Products in the Dietary. — The nutrients 
in milk are produced at less expense for grain and for- 
age than the nutrients in beef, hence from a pecuniary 
point of view, dairy products, as milk and cheese, have 
the advantage. In the case of butter, however, the cost 
usually exceeds that of meat. In older agricultural re- 
gions, where the cost of beef production reaches the 



MILK AND DAIRY PRODUCTS 97 

maximum, dairying is generally resorted to, as it yields 
larger financial returns, and as a result more cheese and 
less beef are used in the dietary. As the cost of meats 
is enhanced, dairy products, as cheese, naturally take 
their place. 



CHAPTER VIII 

MEATS AND ANIMAL FOOD PRODUCTS 

128. General Composition. — Animal tissue is composed 
of the same classes of compounds as plant tissue. In 
each, water makes up a large portion of the weight, 
and the dry matter is composed of nitrogenous and non- 
nitrogenous compounds, and ash or mineral matter. 
Plants and animals differ in composition not so much as 
to the kinds of compounds, although there are differences, 
but more in the percentage amounts of these compounds. 
In plants, with the exception of the legumes, the protein 
rarely exceeds 14 per cent, and in many vegetable foods, 
when prepared for the table, there is less than 2 per 
cent. In meats the protein ranges from 15 to 20 per 
cent. The non-nitrogenous compounds of plants are 
present mainly in the form of starch, sugar, and cellulose, 
while in animal bodies there are only traces of carbohy- 
drates, but large amounts of fat. Fat is the chief non- 
nitrogenous compound of meats ; it ranges between 
quite wide limits, depending upon kind, age, and general 
condition of the animal. Meats contain the same gen- 
eral classes of proteins as the vegetable foods ; in each 
the proteins are made up of albumins, glubulins, albu- 

98 



MEATS AND ANIMAL FOOD PRODUCTS 



99 



minates, peptone-like bodies, and insoluble proteids. 
The larger portion of the protein of meats and cereals 
is in insoluble forms. The meat juices, which contain 
the soluble portion of the proteins, constitute less than 
5 per cent of the nitrogenous compounds. Meats con- 
tain less amid substances than plants, in which the amids 




Fig. 26. — Meat and Extractive Substances. 



are produced from ammonium compounds and are sup- 
posed to be intermediate products in the formation of 
proteids, while in the animal body they are derived from 
the proteids supplied in the food and, it is generally be- 
lieved, cannot form proteids. Albuminoids make up 
the connective tissue, hair, and skin, and are more abun- 
dant in animal than in plant tissue. One of the chief 
albuminoids is gelatine. Both plant and animal foods 



lOO HUMAN FOODS AND THEIR NUTRITIVE VALUE 

undergo bacterial changes resulting in the production of 
alkaloidal bodies known as ptomaines, of which there 
are a large number. These are poisonous and are what 
cause putrid and stale meat to be unwholesome. The 
protein in meat differs little in general composition from 
that of vegetable origin ; differences in structure and 
cleavage products between the two are, however, notice- 
able. 

While meats from different kinds of animals have 
somewhat the same general composition, they differ in 
physical properties, and also in the nature of the various 
nutrients. For example, pork contains less protein than 
beef, but the protein of pork is materially different from 
that of beef, as a larger portion is in the form of soluble 
proteids, while in beef more is present in an insoluble 
form. Not only are differences in the percentage of 
individual proteins noticeable, but there are equally as 
great differences in the fats. As for example : some of 
the meats have a larger proportion of the fat as stearin 
than do others. Hence meats differ in texture and taste 
more than in nutritive value, due to the variations in the 
percentage of the different proteins, fats, and extractive 
material, rather than to differences in the total amounts 
of these compounds. The taste and flavor of meat is to 
a large extent influenced by the amount of extractive 
material. 

While the nutrients of meats are divided into classes, 
as proteins and fats, there are a large number of sepa- 
rate compounds which make up each of the individual 



MEATS AND ANIMAL FOOD PRODUCTS 



lOI 



classes, and there are also small amounts of compounds 
which are not included in these groups. 

129. Beef. — About one half of the weight of beef is 
water ; the lean meat contains a much larger amount 




Fig. 27. — Standard Cuts of Beef. 
(From Ofifice of Experiment Station Eulletin.) 

than the fat. As a rule, the parts of the animal that 
contain the most fat contain the least water. In some 
meats there is considerable refuse, 25 to 30 per cent. 
In average meat about 12 per cent of the butcher's 
weight is refuse and non-edible parts.'** A pound of 
average butcher's meat is about one half water, and over 



I02 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

lo per cent waste and refuse, which leaves less than 
40 per cent fat and protein. Meat is generally con- 
sidered to have a high nutritive value, due to the com- 
paratively large amounts of fat and protein. Beef 
contains more protein than any vegetable food, except 
the legumes, and from i to 1.5 per cent mineral matter, 
exclusive of bone. Some of the mineral matter is chemi- 
cally united with the protein and other compounds. 
While figures are given for average composition of beef, 
it is to be noted that wide variations are frequently to 
be met with, some samples containing a much larger 
amount of waste and trimmings than others, and this 
influences the per cent of the nutritive substances. In 
making calculations of nutrients consumed, as in dietary 
studies, the figures for average composition of meat 
should be used only in cases where the samples do not 
contain an excess either of fat or trimmings.*^ When 
very lean, there is often a large amount of refuse, and 
the meat contains less dry matter and is of poorer flavor 
than from animals in prime condition. In the case of 
very fat animals, a large amount of waste results, and 
the flavor is sometimes impaired. 

130. Veal differs from beef in containing a smaller 
amount of dry matter, richer in protein, but poorer in fat. 
Animals differ in composition at different stages of 
growth in much the same way as plants. In the earlier 
stages protein predominates in the plant tissue, while 
later the carbohydrates are added in larger amounts. 



MEATS AND ANIMAL FOOD PRODUCTS 



103 



reducing the percentage content of protein. In animals 
the same is noticeable. Young animals are, pound for 
pound, richer in protein than old animals. While in the 
case of vegetables the increase in size, or rotundity, is 
due to starch and carbohydrates, in animals it is due to 
the addition of fat. But plants, Hke animals, observe 
the same general laws as to changes in composition at 
different stages of growth. 




Fig. 28. — Standard Cuts of Mutton. 
(From Ofifice of Experiment Station Bulletin.) 



131. Mutton. — There is about the same amount of 
refuse matter in mutton as in beef. In a side of mutton 
about 19 per cent are trimmings and waste, and in a 
side of beef 18.5 per cent. Mutton, as a rule, contains 
a little more fat and dry matter than beef, and some- 
what less protein. A side of beef, as purchased, con- 



I04 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

tains about 50 per cent of water, 14.5 per cent protein, 
and 16.8 per cent of fat, while a side of mutton, as pur- 
chased, contains 42.9 per cent water, 12.5 per cent 
protein, and 24.7 per cent fat. A pound of beef yields 
a smaller number of calories by 25 per cent than a 
pound of mutton. At the same price per pound more 
nutrients can be purchased as mutton than as beef. 
The differences in composition between lamb and 
mutton are similar to those between veal and beef ; viz. 
a larger amount of water and protein and a smaller 
amount of fat in the same weight of the young animals. 
Differences in composition between the various cuts of 
lamb are noticeable. The leg contains the least fat 
and the most protein, while the chuck is richest in fat 
and poorest in protein. As in the case of beef, many 
of the cheaper cuts contain as much or more nutrients 
than the more expensive cuts. They are not, however, 
as palatable and differ as to toughness and other physi- 
cal characteristics. 

132. Pork is characterized by a high per cent of fat 
and a comparatively low per cent of protein. It is gen- 
erally richest in fat of any of the meats. The per cent 
of water varies with the fatness of the animal ; in very 
fat animals there is a smaller amount, while lean ani- 
mals contain more. In lean salt pork there is about 20 
per cent water, and in fat salt pork about 7 per cent. 
There is less refuse and waste in pork than in either 
beef or mutton. Ham contains from 14 to 15 per cent 



MEATS AND ANIMAL FOOD PRODUCTS 



105 



of refuse, and bacon about 7 per cent. Bacon has 
nearly twice as much fat and a smaller amount of pro- 
tein than ham. A pound of bacon, as purchased, will 
yield nearly twice as much energy or fuel value as a 
pound of ham. Digestion experiments show that bacon 
is quite readily and completely digested and is often a 




Fig. 29. — Standard Cuts of Pork. 
(From Office of Experiment Station Bulletin.) 

cheaper source of fat and protein than other meats. 
There is about three times as much fat in bacon as in 
beef. When prepared for the table bacon contains 
from 40 to 50 per cent of fat. A pound of high grade, 
lean bacon furnishes from o.i to 0.3 of a pound of digest- 
ible protein and from 0.4 to 0.6 of a pound of digestible 
fat, which is about two thirds as much fat as is found 
in butter. Bacon contains nearly as much digestible 



Io6 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

protein as other meats and from two to three times as 
much fat, making it, at the same price per pound, a 
cheaper food than other meats. In salt pork there is 
from 60 to 85 per cent of fat, and less protein than in 
bacon. The protein and fat of pork differ from those 
in beef not only in percentage amounts, but also in the 
nature of the individual proteins and fats. The com- 
position of pork varies with the nature of the food that 
is consumed by the animal. Experiments show that 
it is possible by judicious feeding in the early stages of 
growth to produce pork with the maximum of lean 
meat and the minimum of fat. After the animal has 
passed a certain period, it is not possible by feeding to 
materially influence the percentage of nutrients in the 
meat. The flavor, too, of pork, as of other meats, is 
dependent largely upon the nature of the food the 
animal consumes. When there is a scant amount of 
available protein in the ration, the meat is dry, nearly 
tasteless, and contains less of the soluble nitrogenous 
compounds which impart flavor and individuality. 

133. Lard is prepared from the fat of swine, and is 
separated from associated tissue by the action of heat. 
A large amount of fat is found lining the back of 
the abdominal cavity, and this is known as leaf lard. 
Slight differences are noticeable in the composition and 
quality of lard made from different parts of the hog. 
Leaf lard is usually considered the best. Lard is com- 
posed of the three fats, olein, stearin, and palmatin, and 



MEATS AND ANIMAL FOOD PRODUCTS I07 

has a number of characteristic physical properties, as 
specific gravity, melting point, iodine absorption num- 
ber, as well as behavior with various reagents, and 
these enable the mixing of other fats with lard to be 
readily detected. Lard is used in the preparation of 
oleomargarine, and it is also combined with various 
vegetable oils, as cotton-seed oil, in the making of imita- 
tion or compound lards. *^ Lard substitutes differ little 
in general composition from pure lard, except in the 
structure of the crystals and the percentage of the vari- 
ous individual fats. 

134. Texture and Toughness of Meats. —^ In discuss- 
ing the texture of meats, Professor Woods states : ^^ 

" Whether meats are tough or tender depends upon two things : 
the character of the walls of the muscle tubes and the character of 
the connective tissues which bind the tubes and muscles together. 
In young and well-nourished animals the tube walls are thin and 
delicate, and the connective tissue is small in amount. As the ani- 
mals grow older or are made to work (and this is particularly true 
in the case of poorly nourished animals), the walls of the muscle 
tubes and the connective tissues become thick and hard. This is 
the reason why the flesh of young, well-fed animals is tender and 
easily masticated, while the flesh of old, hard-worked, or poorly fed 
animals is often so tough that prolonged boiling or roasting seems 
to have but little effect on it. 

'' After slaughtering, meats undergo marked changes in texture. 
These changes can be grouped under three classes or stages. In 
the first stage, when the meat is just slaughtered, the flesh is soft, 
juicy, and quite tender. In the next stage the flesh stiff"ens and the 
meat becomes hard and tough. This condition is known as rigor 
mortis, and continues until the third stage, when the first changes of 



Io8 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

decomposition set in. In hot climates the meat is commonly eaten 
in either the first or second stage. In cold climates it is seldom 
eaten before the second stage, and generally, in order to lessen the 
toughness, it is allowed to enter the third stage, when it becomes 
soft and tender, and acquires added flavor. The softening is due in 
part to the formation of lactic acid, which acts upon the connective 
tissue. The same effect may be produced, though more rapidly, by 
macerating the meat with weak vinegar. Meat is sometimes made 
tender by cutting the flesh into thin slices and pounding it across 
the cut ends until the fibers are broken,'^ 

135. Influence of Cooking upon the Composition of 

Meats. ^' — It is believed by many that losses are pre- 
vented and the nutritive value conserved when, in the 
cooking of meat, it is placed directly into boiling water 
rather than into cold water and then brought to the 
boiling point and cooked. Extensive experiments have 
been made by Dr. Grindley in regard to this and other 
points connected with the cooking of meats, and in gen- 
eral it was found that the temperature of the water in 
which the meat was placed made little difference in 
its nutritive value or the amount of material extracted. 
It was found that by both methods there was dissolved 
2.3 per cent of the protein matter, i per cent of the 
nitrogenous extractives, 1.6 per cent of non-nitrogenous 
material, and 0.8 per cent of ash, of the raw meat, which 
was equivalent to about 13 per cent of the total proteid 
material and 81 per cent of the ash. The cold water 
extract contained bodies coagulated by heat. Cold 
water did not extract any of the fat, but during the pro- 
cess of cooking, appreciable amounts were lost mechani- 



MEATS AND ANIMAL FOOD PRODUCTS I09 

cally. Cooked meats were found to be less soluble in 
cold water than raw meats. During the process of 
boiling, meat shrinks in weight about 40 or 45 per cent, 
depending mainly upon the size of the pieces and the 
content of fat. The loss in weight is practically a loss 
of water, and the loss of nutrients, all told, amounts to 
about 4 per cent, or more, depending upon the mechan- 
ical loss.'^^ But slight differences were found in the 
composition of the meats cooked three and five hour 
periods. 

"Careful study in this laboratory has shown that when meat is 
cooked in water at 80° to 85° C, placing meat in hot or cold water 
at the start has little effect on the amount of nutrients in the meat 
which passes into the broth. The meat was in the form of cubes, one 
to two inches, and in pieces weighing from one to two pounds. 

'' It is commonly supposed that when meat is plunged into boiling 
water, the albumin coagulates and forms a crust, which prevents the 
escape of nutritive materials into the broth. It is also believed that 
if a rich broth is desired, to be used either as a soup or with the meat 
as a stew, it is more desirable to place the meat in cold water at the 
start. From the results of these experiments, however, it is evident 
that, under these conditions, there can be little advantage in using 
hot or cold water at the beginning. When meats were cooked by 
dry heat, as in roasting, a larger amount of nutrients was rendered 
soluble in water than during boiling. The losses of nutrients were 
much smaller when meats were cooked by dry heat than when cooked 
in water, being on the average, water 35 per cent, nitrogenous extrac- 
tives 9 per cent, non-nitrogenous extractives 17 per cent, fat 7 per 
cent, ash 12 per cent, and a small loss of protein.*' 

The nutrients in the broth of the meat started in 
hot water amounted to about i per cent of protein, 



no HUMAN FOODS AND THEIR NUTRITIVE VALUE 

I per cent of fat, and 0.5 per cent of ash, the amount of 
nutrients being directly proportional to the length of 
time and temperature of the cooking. In general, the 
larger the pieces, the smaller the losses. Beef that has 
been used in the preparation of beef tea loses its extrac- 
tive materials, which impart taste and flavor, but there 
is only a small loss of actual nutritive value. Clear 
meat broth contains little nutriment — less than unfiltered 
broth. Most of the nitrogenous material of the broth is 
in the form of creatin, sarkin, and xanthin, nitrogenous 
extractives or amid substances having a much lower 
food value than proteids. Experiments show that some 
of these extractives have physiological properties slightly 
stimulating in their action, and it is believed the stimulat- 
ing effect of a meat diet is in part due to these. ^^ They 
are valuable principally for imparting taste and flavor, 
and cannot be regarded as nutrients. The variations in 
taste and flavor of meats from different sources are due 
largely to differences in extractive material. 

" In general, the various methods of cooking materially modify the 
appearance, texture, and flavor of meat, and hence its palatability, but 
have little effect on total nutritive value. Whether it be cooked in 
hot water, as in boiling or stewing, or by dry heat, as in roasting, 
broiling, or frying, meat of all kinds has a high food value, when 
judged by the kind and amount of nutrient ingredients which are 
present." ^'^ 

Beef extracts of commerce contain about 50 per cent of 
extractive matters, as amids, together with smaller 
amounts of soluble proteids ; ash, mainly added salt, is 



MEATS AND ANIMAL FOOD PRODUCTS III 

also present in liberal amounts (20 per cent). Beef 
extracts have condimental value imparting taste and 
flavor, which make them useful for soup stocks, but 
they furnish little in the way of nutritive substance. 

136. Miscellaneous Meat Products. — By combining 
different parts of the same animal, or different meats, a 
large number of products known as sausage are made. 
These vary in composition with the ingredients used. 
In general, they are richer in fat than beef and contain 
about the same amount of protein. Potato flour and 
flour from cereals are sometimes used in their prepara- 
tions, but the presence of any material amount, unless 
so stated on the package, is considered an adulter- 
ant. 

Pickled meats are prepared by the use of condiments, 
as salt, sugar, vinegar, and saltpeter. During the smok- 
ing and curing of meats, no appreciable losses of nutri- 
ents occur.^^ The smoke acts as a preservative, and 
imparts condimental properties. Saltpeter (potassium 
nitrate) has been used from earliest times in the prepa- 
ration of meats ; it preserves color and delays fermenta- 
tion changes. When used in moderate amounts it 
cannot be regarded as a preservative or injurious to 
health. Excessive amounts, however, are objectionable. 
Smoked meats, prepared with or without saltpeter, give 
appreciable reactions for nitrites, compounds formed 
during combustion of the wood by which the meat was 
smoked. Many vegetables contain naturally much 



112 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

larger amounts of nitrates, taken from the soil as food, 
than meat that has been preserved with saltpeter.^'*^ 

137. Poultry. — The refuse and waste from chickens, 
as purchased on the market, ranges from 15 to 30 per 
cent. The fat content is much lower than in turkeys or 
ducks, the largest amount being found in geese. The 
edible portion of all fowls is rich in protein, particularly 
the dark meat, and the food value is about equal to that 
of meat in general. When it is desired to secure a large 
amount of protein with but little fat, chicken supplies 
this, perhaps, better than any other animal food. A 
difference is observed in the composition of the meat of 
young and old fowls similar to that between beef and 
veal. The physical composition and, to a slight extent, 
the solubility of the proteids are altered by prolonged 
cold storage, the difference being noticeable mainly in the 
appearance of the connective tissue of the muscles. In 
discussing poultry as food, Langworthy states : ^^ 

"A good, fresh bird shows a well-rounded form, with neat, compact 
legs, and no sharp, bony angles on the breast, indicating a lack of 
tender white meat. The skin should be a clear color (yellow being 
preferred in the American market) and free from blotches and pin 
feathers ; if it looks tight and drawn, the bird has probably been 
scalded before being plucked. The flesh should be neither flabby 
nor stiff, but should give evenly and gently when pressed by the 
finger." 

138. Fish. — From 30 to 60 per cent of the weight 
of fresh fish is refuse. The edible portion contains 



MEATS AND ANIMAL FOOD PRODUCTS II3 

from 35 to 50 per cent, and in some cases more, of 
water. The dry matter is rich in protein ; richer than 
many meats. The nutrients in fish range between 
comparatively wide limits, the protein in some cases 
being as low as 6 per cent, in flounder, and in others 
as high as 30 per cent, in dried codfish. The amount 
of fat, except in a few cases, as salmon and trout, 
is small. Salmon is the richest in fat of any of the 
fishes. When salted and preserved, the proportion of 
water is lessened and that of the nutrients is increased. 
Fish can take the place of meat in the dietary, but 
it is necessary to add a larger amount of fat to the ra- 
tion because of the deficiency of most fish in this ingre- 
dient. Fish has about the same digestibility as meats. 
It is believed by many to be valuable because it supplies 
a large amount of available phosphates. Analyses, 
however, show that the flesh of fish contains no more 
phosphorus compounds than meats in general, and its 
food value is due to protein rather than to phosphates.^* 
Fish appears to be as completely and easily digested 
as meats. Differences in flavor, taste, and palatability are 
due to small amounts of flavors and extractive materials, 
varying according to the food consumed by the fish 
and the conditions under which they lived. The flesh 
of fish decays more readily than that of other meats 
and produces ptomaines, or toxic substances, which are 
the result of fermentation changes usually associated 
with putrefaction. Cases of poisoning from eating un- 
sound fish are not infrequent. ^*^ 



114 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

Shellfish have about the same general composition as 
fish. In clams there is a larger amount of dry matter 
than in oysters, which contain about 12 per cent, half 
of which is protein. When placed in fresh water, the 
oyster increases in size and undergoes the process 
known as "fattening." Oftentimes impure water is 
used for this purpose, which makes the eating of raw 
oysters a questionable practice from a sanitary point 
of view, as the water in which they are floated often 
contains disease-producing germs, as typhoid. During 
the process of fattening, although the oyster increases 
in size and weight, it decreases in percentage of nutri- 
ents. In discussing the composition of oysters, 
Atwater states : '^ 

"They come nearer to milk than almost any other food material 
as regards both the amounts and relative proportions of nutrients." 

139. Eggs, General Composition. — Eggs are a type 
of concentrated nitrogenous food. About 75 per cent 
(shell removed) is water, about one third is yolk, and 
a little over 50 per cent is albumin or white. The 
shell makes up from 10 to 12 per cent of the weight. 
The yolk and white differ widely in composition. 
The yolk contains a much larger per cent of solids than 
the white, and is rich in both fat and protein, from a 
third to a half of the weight being fat. The white has 
about the same amount of water, 88 per cent, as aver- 
age milk, but, unlike milk, the dry matter is mainly 
albumin. The entire egg (edible portion) contains about 



MEATS AND ANIMAL FOOD PRODUCTS 



IIS 



equal parts of fat and protein; 12 to 13 per cent of 
each and an appreciably large amount of ash or mineral 
matter, — from 0.8 to i per 
cent, consisting mainly of 
phosphates associated with 
the albumin. There is no 
material difference in chem- 
ical composition between 
white and dark shelled eggs, 
or between eggs with differ- 
ent colored yolks. It is 
simply a question of color- 
ing matter. The egg is in- 
fluenced to an appreciable 
extent by feed and general 
care of the fowls. The 
Qgg and the potato contain fig. 30. 
about the same amount of 
water. They are, however, distinct types of food, 
the potato being largely composed of carbohydrates 
and the egg of protein and fat. Eggs resemble meat 
somewhat in general composition, although they con- 
tain rather less of protein and fat. When eggs are 
boiled there is a loss of weight due to elimination of 
water; otherwise the composition is unaltered, the 
coagulation of the albumin, as stated in Chapter I, 
consisting simply in a rearrangement of the atoms of 
the molecule. The egg is particularly valuable in the 
dietary of the convalescent, when it is desired to secure 



^^^^^^l^&/u j e ^^^^^H 


^^^■' V/ito-r ^^H 


^^^I^^H ^^^^H 





Graphic Composition 
OF AN Egg. 



Il6 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

the maximum amount of phosphorus in organic combi- 
nation. 

The flavor of eggs is in part due to the food suppHed 
to the fowls, as well as the age of the egg. Experi- 
ments show that onions and some other vegetables, 
when fed to fowls, impart odors and taste to the eggs. 
The keeping qualities of eggs are also dependent upon 
the food supplied. In experiments at the Cornell Ex- 
periment Station, when hens were fed on a narrow, 
nitrogenous ration, a large number of eggs were pro- 
duced containing the minimum amount of solid matter 
and of poor keeping quality, while a larger sized egg of 
better keeping quality was obtained when a variety of 
foods, nitrogenous and non-nitrogenous, was supplied. 

140. Digestibility of Eggs. — Digestion experiments 
show that there is but little difference in the digestibil- 
ity of eggs cooked in different ways. A noticeable dif- 
ference, however, is observed in the rapidity with which 
the albumin and proteids are dissolved in a pepsin solu- 
tion. In general, it was found that, when the albumin 
was coagulated at a temperature of i8o°, it was more 
rapidly and completely dissolved in the pepsin than 
when coagulated at a temperature of 212°. When eggs 
were cooked at a temperature of 212°, the hard-boiled 
eggs appeared to be slightly more digestible than the 
soft-boiled eggs, but the digestion was not as complete 
as when the cooking was done at a temperature of 180° ; 
then no difference in digestibility was found between 



MEATS AND ANIMAL FOOD PRODUCTS II7 

eggs cooked for a short or a long time. The egg is 
one of the most completely digested of all foods, 
practically all the protein and fat being absorbed and 
available to the body. Langworthy, in discussing Joris- 
senne's investigations on the digestibility of eggs, 
states : ^^ 

" The yolk of raw, soft-boiled, and hard-boiled eggs is equally 
digestible. The white of soft-boiled eggs, being semi-liquid, offers 
little more resistance to the digestive juices than raw white. The 
white of a hard-boiled egg is not generally very thoroughly masti- 
cated. Unless finely divided, it offers more resistance to the diges- 
tive juices than the fluid or semi-fluid white, and undigested particles 
may remain in the digestive tract many days and decompose. From 
this deduction it is obvious that thorough mastication is a matter of 
importance. Provided mastication is thorough, marked differences 
in the completeness of digestion of the three sorts of eggs, in the 
opinion of the writer cited, will not be found.'' 

141. Use of Eggs in the Dietary. — When eggs are at 
the same price per dozen as meat is per pound, they 
furnish a larger aniount of nutrients. In general, a 
dozen eggs have a little higher food value than a pound 
of meat. Eggs are usually a cheaper source of food 
because a smaller amount is served than of meat. 
When eggs are 25 cents per dozen, the cost of ten eggs 
for a family of five is less than that of a pound or a 
pound and a quarter of beef at 22 cents per pound. 
The meat, however, would furnish the larger amount of 
nutrients. Eggs are valuable, too, in the dietary be- 
cause they are frequently combined with flour, cereal 



Il8 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

products, and vegetables, which contain a large amount 
of starch, and some of which contain small amounts of 
protein. This combination furnishes a balanced ration, 
as well as secures palatability and good mechanical 
combination of the foods. Eggs in combination with 
flour, sugar, butter, and other materials have equally 
as ofreat a value as when used alone and as a substitute 
for meat. 

Eggs vary in weight from 17.5 to 28 ounces, and 
more per dozen. They should be purchased and sold by 
weight. When stored, eggs lose weight. The egg can- 
not be considered as entirely germ proof, and care is 
necessary in its handling and use, the same as with 
other food articles. The cause of the spoiling of eggs 
is due largely to exterior bacterial infection. 

CANNED MEATS 

142. General Composition. — Canned meats differ but 
little in composition from fresh meats. Usually during 
the process of cooking and canning there is a slight 
increase in the amount of dry matter, but the relative 
proportion of protein and fat is about the same as in 
fresh meat. It is frequently stated that the less salable 
parts are used in the preparation of canned meats, as 
it is possible by cooking and the addition of condiments 
to conceal the inferior physical properties. As to the 
accuracy of these statements, the author is unable to 
say. The shrinkage or loss in weight during canning 



MEATS AND ANIMAL FOOD PRODUCTS II9 

amounts to from 30 to 40 per cent. The liquids in 
which the cooking and parboiling are done are some- 
times used in the preparation of beef extracts. Salt, 
saltpeter, and condiments are generally added during 
the canning process. Saltpeter is used, as it assists in 
retaining the natural color and prevents some objection- 
able fermentation changes. In moderate amounts it 
is not generally considered an adulterant. An exten- 
sive examination by Wiley and Bigelow of packing- 
house products and preserved meats showed that of 
the latter only a small amount contained objectionable 
preservatives. The authors, after an extended inves- 
tigation, reported favorably upon their composition and 
sanitary value, saying they found '' so little to criti- 
cise and so much to commend in these necessary prod- 
ucts." In this bulletin they do not classify saltpeter 
as an adulterant.^^ 

Where fresh meats cannot be secured, canned meats 
are often indispensable. Usually the nutrients of 
canned meats cost more than those of fresh meats, 
and in their use as food much care should be ex- 
ercised to prevent contamination after opening the 
cans. Occasionally the meat contains ferment mate- 
rials that have not been entirely destroyed during 
cooking, and these, when the cans are stored in warm 
places, develop and cause deleterious changes to 
occur. Consequently canned meats should be stored 
at a low temperature. By recent congressional act, 
these preparations are now made under the super- 



I20 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

vision of government inspectors. All diseased animals 
are rejected, and the sanitary conditions under which 
the meat is prepared have been greatly improved. 
Formerly, the most frequent forms of adulteration 
were substitution of one meat for another, as the 
mixing of veal with chicken, and the use of preserva- 
tives, as borax and sulphites. While the cost of the 
nutrients in canned meats is generally much higher 
than in fresh meats, the latter are not always easily 
obtained, or capable of being kept for any length of 
time, and hence canned meats are often indispensable. 



CHAPTER IX 
CEREALS 

143. Preparation and Cost of Cereals. — The grains 
used in the preparation of cereal foods are wheat, oats, 
corn, rice, and, to a less extent, barley and rye. For 
some of these the entire cleaned grain is ground or 
pulverized, while for others the bran and germ are first 
removed. In order to improve their keeping qualities, 
they are often sterilized before being put up in sealed 
packages. Special treatment, as steaming or malting, 
is sometimes given to impart palatability and to lessen 
the time required for cooking. As a class, the cereal 
foods are clean, nutritious, and free from adulteration. 
Extravagant claims are sometimes made as to their 
food value, and frequently excessive prices are charged, 
out of proportion to the cost of the nutrients in the raw 
material. Within recent years the number of cereal 
preparations has greatly increased, due to improve- 
ments and variations in the methods of manufacture.^^ 

Cereal foods are less expensive than meats and the 
various animal food products. They contain no refuse, 
are easily prepared for the table, and may be kept 
without appreciable deterioration. Some of the ready- 

121 



122 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

to-eat brands are cooked, dried, and crushed, and sugar, 
glucose, salt, and various condimental materials added 
to impart taste. Others contain malt, or are subjected 
to a malting or germinating process to develop the 
soluble carbohydrates, and such foods are sometimes 
called predigested. It is believed that the cereals are 
being more extensively used in the dietary, which is 
desirable both from an economic and a nutritive point 
of view. Special care is necessary in the cooking and 
preparation of cereals for the table, in order to develop 
flavor and bring about hydration and rupturing of the 
tissues, as explained in Chapter II. 

144. Corn Preparations. — Corn or maize is character- 
ized by a high per cent of fat and starch, and, compared 
with wheat and oats, a low content of protein.^' Re- 
moval of the bran and germ lessens the per cent of fat. 
The germ is removed principally because it imparts 
poor keeping qualities. Many of the corn breakfast 
foods contain i per cent or less of fat and from 8 to 9 
per cent of protein. Coarsely ground corn foods are 
not as completely digested and assimilated as those 
more finely ground. As in the case of wheat products, 
the presence of the bran and germ appears to prevent 
the more complete absorption of the nutrients. Finely 
ground corn meal compares favorably in digestibility 
with wheat flour. Corn flour is prepared by removal 
of the bran and germ and granulation of the more 
starchy portions of the kernel, and has better keeping 



CEREALS 123 

qualities than corn meal from which the bran and germ 
have not been so completely removed. At times corn 
flour has been sufficiently low in price to permit its use 
for the adulteration of wheat flour. The mixing of corn 
and wheat flours, however, is prohibited by law unless 



i 






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^ ^ 


" 


4 


0^ »• ^ 


. ^ . 


^ ..> 






•*•,"* 
' <*'** 






* 

^ 


• ©0 « • . 









Fig. 31. — Corn Starch. 

the product is so labeled. When combined with wheat 
flour, corn bread and various other articles of food are 
prepared, but used alone corn flour is not suitable for 
bread making, because its gluten lacks the binding 
properties imparted to wheat flour by the gHadin. It 
is essential that corn be used with foods of high protein 
content so as to make a balanced ration ; for when it 
forms a large part of the dietary, the ration is apt to be 



124 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

deficient in protein. In a mixed dietary, corn is one of 
the cheapest and best cereals that can be used. Too 
frequently, however, excessive prices are charged for 
corn preparations that contain no more nutrients than 
ordinary corn meal. There is no difference between 
yellow and white corn meal so far as nutritive value is 
concerned. 

145. Oat Preparations are characterized by large 
amounts of both protein and fat. Because of the 
removal of the hulls, they contain more protein than 
the original grain. The oat preparations differ httle in 
chemical composition. They all have about i6 per cent 
of protein, 7 per cent of fat, and 65 per cent of starch, 
and are richer in ash or mineral matter than other 
cereals. The main difference is in method of prepara- 
tion and mechanical composition. Some are partially 
cooked and then dried. Those costing 7 cents or more 
per pound do not contain any greater arq,ount of nutri- 
tive substance than those purchased in bulk at about 
half the price. At one time it was believed that oats 
contained a special alkaloid having a stimulating effect 
when fed to animals. Recent investigations, however, 
show that there is no alkaloidal material in oats, and 
whatever stimulating effect they may have results from 
the nutrients they contain. Occasionally there is an 
appreciable amount of cellulose, or fiber, left in the oat 
preparations, due to imperfect milling. This noticeably 
lowers the digestibility. Oatmeal requires much longer 



CEREALS 



125 



and more thorough cooking than many other cereals, 
and it is frequently used as food when not well pre- 
pared. Digestion experiments show that when oatmeal 
is cooked for four hours or more, it is more readily acted 
upon by the diastase ferment and digested in a shorter 




Fig. 32. —Oat Starch Granules. 

time than oatmeal cooked only a half hour.^ Oatmeal 
is one of the cheapest sources from which protein is 
obtained, and when well cooked it can advantageously 
form an essential part of the ration. Unless thoroughly 
cooked, the oat preparations do not appear to be quite so 
completely or easily digested as some of the other cereals. 



126 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

146. Wheat Preparations differ in chemical composi- 
tion more than those from oats or corn, because wheat 
is prepared in a greater variety of ways. They are 
made either from the entire kernel, including the bran 




Fig. 33. — Wheat Starch Grains. 

and germ, or from special parts, as the granular mid- 
dlings, as in the case of some of the breakfast foods, and 
a few are made into a dough and baked, then dried and 
toasted. Some special flours are advertised as com- 
posed largely of gluten, but only those that have been 
prepared by washing out the starch are entitled to be 
classed as gluten flours.^^ For the food of persons 



CEREALS 127 

suffering from diabetes mellitus physicians advise the 
use of flour low in starch, and this can be made by 
washing and thus removing a portion of the starch from 
wheat flour, as directed in Experiment No. 30. The 
glutinous residue is then used for preparing articles of 
food. Analyses of some of the so-called gluten flours 
show that they contain no more gluten than ordinary 
flour, particularly the low grades. A number of wheat 
breakfast foods are prepared by sterilizing the flour 
middlings obtained after removal of the bran and germ. 
These middlings are the same stock or material from 
which the patent grades of flour are made, and they 
differ from wheat flour only in mechanical structure 
and size of the particles. Where granular wheat mid- 
dlings can be secured in bulk at the same price as 
flour they furnish a valuable and cheap cereal breakfast 
food. 

As to the digestibility and food value, the wheat 
breakfast foods have practically the same as graham, 
entire wheat, or ordinary patent flour, depending upon 
the stock which they contain. Those with large amounts 
of bran and germ are not as completely digested as 
when these parts of the kernel are not included. Wheat 
preparations, next to oats, have the most protein of any of 
the cereal foods. Occasionally they are prepared from 
wheats low in gluten and not suitable for bread-making 
purposes. When purchased in bulk the wheat prepara- 
tions are among the cheapest foods that can be used in 
the dietary.^^ 



128 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

147. Barley Preparations are not so extensively used 
as wheat, oats, and corn. Barley contains a little more 
protein than corn, but not quite so much as wheat ; 
otherwise it is quite similar to wheat in general composi- 
tion. Sometimes in the preparation of breakfast foods 




barley meal is mixed with wheat or corn. Barley is 
supposed to be more readily digested than some of the 
other cereals, because of the presence of larger amounts 
of active ferment bodies, and it is frequently used for 
making an extract known as " barley water," which, 
although it contains very little nutritive value, as less 



CEREALS 



129 



than one per cent of the weight of the barley is rendered 
soluble, is useful in its soothing influence and mechan- 
ical action upon the mucous membrane of the digestive 
tract. 



•^ •• >' -9^ 










Fig. 35. — Rice Starch. 



148. Rice Preparations. — Rice varies somewhat in 
composition, but usually contains a slightly lower per- 
centage of protein than corn and also a smaller amount 
of fat. It is particularly rich in starch, and has the least 



130 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

ash or mineral matter of any of the cereals. In order 
to make a balanced ration, rice should be supplemented 
with legumes and other foods rich in proteids. It is a 
valuable grain, but when used alone it is deficient in 
protein. Rice is digested with moderate ease, but is not 
as completely absorbed by the body as other cereals, 
particularly those prepared by fine grinding or pulver- 
ization. Of late years rice culture has been extensively 
introduced into some of the southern states, and the do- 
mestic rice seems to have sHghtly higher protein content 
than the imported. Rice contains less protein than 
other cereals, and the starch grain is of different con- 
struction. Rice does not require such prolonged cook- 
ing as oatmeal; it needs, however, to be thoroughly 
cooked. 

149. Predigested Foods.^^ 

" It is questionable whether it would be of advantage to a healthy 
person to have his food artificially digested. The body under nor- 
mal conditions is well adapted to utilize such foods as the ordinary 
mixed diet provides, among them the carbohydrates from the cereals. 
Moreover, it is generally believed that for the digestive organs, as 
for all others of the body, the amount of exercise they are normally 
fitted to perform is an advantage rather than the reverse. It has 
been said that 'a well man has no more need of predigested food 
than a sound man has for crutches.' If the digestive organs are out 
of order, it may be well to save them work, but troubles of digestion 
are often very complicated affairs, and the average person rarely has 
the knowledge needed to prescribe for himself. In general, those who 
are well should do their own work of digestion, and those who are 
ill should consult a competent physician.'' — Woods and Snyder. 



CEREALS 131 

150. The Value of Cereals in the Dietary. — Cereals 
are valuable in the dietary because of the starch and 
protein they supply, and the heat and energy they yield. 
They are among the most inexpensive of foods and, 
when properly prepared, have a high degree of palata- 
bility ; then, too, they are capable of being blended in 
various ways with other foods. Some are valuable for 
their mechanical action in digestion, rather than for any 
large amount of nutrients. They do not furnish the 
quantity of mineral matter and valuable phosphates that 
is popularly supposed. They all contain from 0.5 to 1.5 
per cent of mineral matter, of Vv^hich about one third is 
phosphoric anhydrid. In discussing the phosphate con- 
tent of food, Hammersten states :^^ 

" Very little is known in regard to the need of phosphates or 
phosphoric acid. . . . The extent of this need is most difficult to 
determine, as the body shows a strong tendency, when increased 
amounts of phosphorus are introduced, to retain more than is neces- 
sary. The need of phosphates is relatively smaller in adults than 
in young developing animals.'' 

In the coarser cereals, which include the bran and 
germ, there is the maximum amount of mineral matter, 
but, as in the case of graham bread, it is not as completely 
digested and absorbed by the body as the more finely 
granulated products which contain less. The kind of 
cereal to use in the dietary is largely a matter of per- 
sonal choice. As only a small amount is usually eaten 
at a meal, there is Httle difference in the quantity of 
nutrients suppHed by the various breakfast cereals. 





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CHAPTER X 
WHEAT FLOUR 

151. Use for Bread Making. — Wheat is particularly 
adapted to bread-making purposes because of the physi- 
cal properties of the gliadin, one of its proteids. It is 
the gliadin which, when wet, binds together the flour 
particles, enabling the gas generated during bread mak- 
ing to be retained, and the loaf to expand and become 
porous. Wheat varies in chemical composition between 
wide limits; it may contain as high as i6 per cent of 
protein, or as low as 8 per cent ; average wheat has from 
12 to 14 per cent; and with these differences in compo- 
sition, the bread-making value varies. 

152. Winter and Spring Wheat Flours. — There are 
two general classes of wheat : spring wheat and winter 
wheat. The winter varieties are seeded in the fall, and 
the spring varieties, which are grown mainly in the 
Northwestern states, Minnesota, and North and South 
Dakota, and the Canadian Northwest, are seeded in the 
spring and mature in the late summer. Winter wheat 
is confined to more southern latitudes and regions of 
less severe winter, and matures in the early summer. 
There are many varieties of both spring and winter 

^33 



134 HUMAN FOODS AND THEIR NUTRITIVE VALUE 




Fig. 36.— Starchy (light-colored) and Glutinous 
(dark-colored) wheats. 



WHEAT FLOUR 



135 



wheat, although wheats are popularly characterized only 
as hard or soft, depending upon the physical proper- 
ties. The winter wheats 
are, as a rule, more soft 
and starchy than the spring 
wheats, which are usually 
corneous or flinty to differ- 
ent degrees. There is a 
general tendency for 
wheats to become either 
starchy or glutinous, owing 
to inherited individuality of 
the seed and to environ- 
ment. There are often 
found in the same field 
wheat plants yielding hard 
glutinous kernels, and other 
plants producing starchy 
kernels containing 5 per 
cent less proteids. Wheats 
of low protein content do 
not make high-grade flour ; 
neither do wheats of the 
maximum protein content necessarily make the best 
flour. For a more extended discussion of wheat pro- 
teids, the student is referred to Chapter XI. 




Fig. 37. — Longitudinal Section 
OF Wheat Kernel: a, pericarp; 
b, bran layers ; c, aleurone cells ; 
d, germ. (After KONIG.) 



153. Composition of Wheat and Flour. — In addition 
to 12 to 14 per cent proteids, wheat contains 72 to "jG 



136 HUMAN FOODS AND THEIR NUTRITIVE VALUE 



per cent of starch and small amounts of other carbohy- 
drates, as sucrose, dextrose, and invert sugar. The 
ash or mineral matter ranges from 1.7 to 2.3 per cent 
There is also about 2 per cent fiber, 2.25 per cent ether 
extract or crude fat, and about 0.2 per cent organic 
acids. 



Summary : 



Composition of Wheat Flour 



Water 




Per Cent 
12 CO 




Potash 
Soda 








Lime 






Ash 


Magnesia 

Phosphoric anhydrid 
Sulphuric anhydrid 
Other substances 


> 


2.25 


Protein- 
Other n 


Albumin 0.4 
Globulin 0.9 
Gliadin 6.0 
Glutenin 5.3 
Other proteids 04, 
trogenous bodies, as a 


mids, lecethin .... 


13.00 

0.25 

2.25 

2.25 

66.00 


Cellules 

Starch 

Sucrose, 






dextrose, soluble carbohydrates, etc 


2.00 



154. Roller Process of Flour Milling. — Flours vary 
in composition, food value, and bread-making qualities 
with the character of the wheat and the process of 



WHEAT FLOUR 



137 



milling employed. Prior to 1870 practically all wheat 
flour was prepared by grinding the wheat between mill- 
stones ; but with the introduction of the roller process, 




Fig. 38. — Granular Wheat Flour Particles. 



steel rolls were substituted for millstones.^^ By the for- 
mer process a smaller amount of flour was secured from 
the wheat, but with the present improved systems about 



138 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

75 per cent of the weight of the grain is recovered as 
merchantable flour and 25 per cent as wheat offals, 
bran, and shorts. *^^ 

The wheat is first screened and cleaned, then passed 
on to the corrugated rolls, or the first break, where 
it is partially flattened and shghtly crushed and a 
small amount of flour, known as the break flour, 
is separated by means of sieves, while the main portion 
is conveyed through elevators to the second break, 
where the kernels are more completely flattened and 
the granular flour particles are partially separated 
from the bran. The -material passes over several 
pairs of rolls or breaks, each succeeding pair being 
set a Httle nearer together. This is called the gradual 
reduction process, because the wheat is not made 
into flour in one operation. More complete removal 
of the bran and other impurities from the middlings 
is effected by means of sieves, aspirators, and other 
devices, and the purified middlings are then passed 
on to smooth rolls, where the granulation is completed. 
The flour finally passes through silk bolting cloths, 
containing upwards of 12,000 meshes per square inch. 
The dust and fine debris particles are removed at 
various points in the process. The granulation of the 
middlings is done after the impurities are removed, the 
object being first to separate as perfectly as pos- 
sible the middlings from the branny portions of the 
kernel. If the wheat were first ground into a fine 
meal, it would be impossible to secure complete sepa- 




139 



I40 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

ration of the flour from the offal portions of the 
kernel. 

Flour milling is entirely a mechanical process ; the 
flour stock passes from roll to roll by means of eleva- 
tors. According to the number of reductions which the 
middlings and stock undergo, the milling is designated as a 
long or a short reduction system ; the term 4, 6, 8, or 10 
break process means that the stock has been subjected 
to that number of reductions. With an 8-break system 
of mining, the process is more gradual than with a 
4-break, and greater opportunity is afforded for complete 
removal of the bran. In some large flour mills, the 
wheat is separated into forty or more different products, 
or streams, as they are called, so as to secure a better 
granulation and more complete removal of the offals, 
after which many of these streams are brought together 
to form the finished flour. What is known as patent flour 
is derived from the reduction of the middlings, while 
the break flours are recovered before the offals are 
completely removed ; hence they are not of so high 
a grade. No absolute definition can be given, how- 
ever, of the term "patent flour," as usage varies the 
meaning in different parts of the country. 

155. Grades of Flour. — Flour is the purified, refined, 
and bolted product obtained by reduction and granu- 
lation of wheat during and after the removal of the 
branny portions of the wheat kernel. It is defined by 
proclamation of the Secretary of Agriculture, under 



142 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

authority of an act of Congress, as : *' Flour is the 
fine, sound product made by bolting wheat meal, and 
contains not more than thirteen and one half (13.5) 
per cent of moisture, not less than one and twenty- 
five hundredths (1.25) per cent of nitrogen, not more 
than one (i) per cent of ash, and not more than fifty 
hundredths (0.50) per. cent of fiber." 

Generally speaking, flour may be divided into two 
classes, high grade and low grade. To the first class 
belong the first and second patents and, according to 
some authorities, a portion of the straight grade, or 
standard patent flour, and to the second class belong 
the second clear and *'red dog." About 72 per cent 
of the cleaned wheat as milled is recovered in the 
higher grades of flour, and about 2 or 3 per cent as low 
grades, a large portion of which is sold as animal food. 
The high grades are characterized by a lighter color, 
more elastic gluten, better granulation, and a smaller 
number of debris particles. Although the lower grade 
flours contain a somewhat higher percentage of protein, 
they are not as valuable for bread-making purposes 
because the gluten is not as elastic, and consequently 
they do not make as good bread. If the impurities 
from the low grades could be further eliminated, it is 
believed that less difference would exist between high 
and low grade flours. 

Various trade names are used to designate flours, as 
a 95 per cent patent, meaning that 95 per cent of the 
total flour is included in the patent ; or an 85 per cent 



WHEAT FLOUR 



43 



patent, when 85 per cent of all the flour is included in 
that particular patent. If all the flour streams were 
purified and blended, and only one grade of flour made, 



^ *B HI'' 'fli' '-iii '^ • 

i-«'9 « • « m m m m 
■:*";• 4Mm.m mm m'%i 

■p 9 *vi ' IP ' 



Fig. 41. — Silk Bolting Cloth used in Manufacture of Flour, 
magnified. 



it would be called a 100 per cent patent. An 85 per 
cent patent is a higher grade flour than a 95 per cent 
patent. 

156. Composition of Flour. — The composition of the 
different grades of flour made from the same wheat is 
given in the following table : ^^ 



144 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

Composition, Acidity, and Heats of Combustion of Flours 
AND Other Milled Products of Wheat 



Milled Product 


a 
< 




< 


(A 

< a 

£ 


X 

< 


Acidity 

CALCULATED 

AS Lactic 
Acid 


Heat of 

Combustion 

PER Gram 

Determined 




% 


% 


% 


% 


% 


% 


Calories 


First patent flour . . 


10.55 


11.08 


1. 15 


76.85 


0.37 


008 


4032 


Second patent flour 


10.49 


11.14 


1.20 


76.75 


0.42 


0.08 


4006 


Straight * or standard 
















patent flour . . . 


10.54 


11.99 


I.6I 


75-36 


0.50 


0.09 


4050 


First clear grade flour . 


10.13 


1374 


2.20 


73-13 


0.80 


0.12 


4097 


Second clear grade flour 


10.08 


15-03 


377 


69-37 


1-75 


0.56 


4267 


'• Red dog'' flour . . 


9.17 


18.98 


7.00 


61.37 


3-48 


0.59 


4485 


Shorts 


8.73 


14.87 


6.37 


65.47 


4.56 


0.14 


4414 


Bran 


9.99 


14.02 


4-39 


65.54 


6.06 


0.23 


4198 


Entire-wheat flour . . 


10.81 


12.26 


2.24 


73-67 


1.02 


0.32 


4-32 


Graham flour .... 


8.61 


12.65 


2.44 


7458 


1.72 


0.18 


4148 


Wheat 


8.50 


12.65 


2.36 


74.69 


1.80 


0.18 


4140 



In the table it will be noted that there is a gradual 
increase in protein content from first patent to ''red 
dog," the largest amount being in the "red dog" flour. 
Although "red dog" contains the most protein, it is by 
far the poorest flour in bread-making qualities, and in 
the mining of wheat often it is not separated from the 
offals, but is sold as an animal food. It will also be 
seen that there is a gradual increase in the ash content 
from the hisfhest to the lowest o-rades of flour, the 



Straight flour includes the first and second patents and first clear grade. 



WHEAT FLOUR 1 45 

increase being practically proportional to the grade, — 
the most ash being in the lowest grade. The grade to 
which a flour belongs can be determined more accu- 
rately from the ash content than from any other constit- 
uent. Patent grades of flour rarely contain more than 
0.55 per cent of ash, — the better grades less than 0.5 per 
cent. The more completely the bran and offals are re- 
moved during the process of milling, the lower the per 
cent of ash. The ash content, however, cannot be 
taken as an absolute guide in all cases, as noticeable 
variations occur in the amount of mineral matter or ash 
in different wheats ; starchy wheats that have reached 
full maturity often contain less than hard wheats grown 
upon rich soil where the growing season has been short, 
and from such wheats a soft, straight flour may have 
as low a per cent of ash as a hard first patent flour. 
When only straight or standard patent flour is manufac- 
tured by a mill, all of the flour is included which would 
otherwise be designated first and second patents and 
first clear. 

157. Graham and Entire Wheat Flours. — When the 
germ and a portion of the bran are retained in the 
flour, and the particles are not completely reduced, the 
product is called '' entire wheat flour." The name does 
not accurately describe the product, as it includes all of 
the flour and only a portion of the bran, and not the 
entire wheat kernel. Graham flour is coarsely granu- 
lated wheat meal. No sieves or bolting cloths are 

L 



146 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

employed in its manufacture, and many coarse, unpul- 
verized particles are present in the product.^^ 

158. Composition of Wheat Offals. — Bran and shorts 
are characterized by a high percentage of fiber, or cel- 
lulose. The ash, fat, and protein content of bran are all 
larger than of flour. The protein, however, is not in the 
form of gluten, but is largely albumin and globulins, ^^ 




Fig. 42. — Flour and Gluten. 
I, flour; 2, dougli; 3, moist gluten; 4, dry gluten. 

which are mainly in the aleurone layer of the wheat 
kernel, and are inclosed in branny capsules, and conse- 
quently are in a form not readily digested by man. 

The germ is generally included in the shorts, although 
occasionally it is removed for special commercial pur- 
poses. It is sometimes sterilized and used in breakfast 
food products. The germ is rich in oil and is excluded 
from the flour mainly because it has a tendency to be- 
come rancid and to impart to the flour poor keeping 



WHEAT FLOUR 1 47 

qualities. Wheat oil has cathartic properties, and it is 
believed the physiological action of whole wheat and 
graham bread is in part due to the oil. The germ is 
also rich in protein, mainly in the form of globulins and 
proteoses. A dough cannot be made of pure germ, 
because it contains so little of the gliadin and glutenin. 

159. Aging and Curing of Flour. — Flours well milled 
and made from high-grade, cleaned wheat generally 
improve in bread-making value when stored in clean, 
ventilated warehouses for periods of three to six months.^ 
High-grade flour becomes drier and whiter and pro- 
duces bread of slightly better quality when properly 
cured by storage. If the flour is in any way unsound, 
it deteriorates during storage, due to the action of fer- 
ment bodies. Wheat also, when properly cleaned and 
stored, improves in milling and bread-making value. 
Certain enzymic changes appear to take place which 
are beneficial. Wheats differ materially from year to 
year in bread-making value, and those produced in 
seasons when all the conditions for crop growth are 
normal do not seem to be so much improved by storing 
and aging, either of the wheat or the flour, as when the 
growing season has been unfavorable. When wheat is 
stored, specific changes occur in both the germ and the 
cells of the kernel; these changes are akin to the ripen- 
ing process, and appear to be greater if, for any reason, 
the wheat has failed to fully mature or is abnormal in 
composition. 



148 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

The flour yield of wheat is in general proportional to 
the weight per bushel of the grain, well-filled, heavy 
grain producing more flour than light grain.^^ The 
quality of the flour, however, is not necessarily propor- 
tional to the weight of the grain. It is often necessary 
to blend different grades and types of wheat in order to 
secure good flour. 

160. Macaroni Flour is made from durum wheat, ac- 
cording to Saunders a variety of hard, spring wheat. 
It is best grown in regions of restricted rainfall. Durum 
and other varieties of hard spring wheat grown under 
similar conditions, differ but little in general chemical 
composition, except that the gluten of durum appears to 
have a different percentage of gliadin and glutenin, and 
the flour has a more decided yellow color. Durum 
wheats are not generally considered as valuable for 
bread making as other hard wheat. They differ widely 
in bread-making value, some being very poor, while 
others produce bread of fair quality. *^''^ 

161. Color. — The highest grades of flour are white 
in color, or of a slight creamy tinge. Dark-colored, 
slaty, and gray flours are of inferior quality, indicating 
a poor grade of wheat, poor milling, or a poor quality of 
gluten. Flours, after being on the market for a time, 
bleach a little and improve to a slight degree in color. 
Color is one of the characteristics by which the com- 
mercial value of flour is determined ; the whiter the 



WHEAT FLOUR 1 49 

flour, the better the grade, provided other properties are 
equal.^ The color, however, should be a pure or cream 
white. Some flours have what is called a dead white 
color, and, while not objectionable as far as color is con- 
cerned, they are not as valuable for bread-making and 
general commercial purposes. One of the principal 
trade requirements of a flour is that it possess a cer- 
tain degree of whiteness and none of the objectionable 
shades mentioned. 

To determine the color of a flour, it is compared with 
a standard. If it is a winter wheat flour, one of the best 
high-grade winter patents to be found on the market 
is selected, and the sample in question is compared with 
this ; if it is a spring wheat patent flour, one of the best 
spring wheat patent grades is taken as the standard. 
In making the comparison, the flours should be placed 
side by side on a glass plate and smoothed with the 
flour trier, the comparison being made preferably by a 
north window. Much experience and practice are neces- 
sary in order to determine with accuracy the color value 
of a flour. 

162. Granulation. — The best patent grades of flour 
contain an appreciable amount of granular middlings, 
which have a characteristic "feel" similar to fine, sharp 
sand. A flour which has no granular feeHng is not usu- 
ally considered of the highest grade, but is generally 
a soft wheat flour of poor gluten. However, a flour 
should not be too coarsely granulated. The percentage 



150 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

amounts of the different grades of stock in a flour can be 
approximately determined by means of sieves and differ- 
ent sized bolting cloths. To test a flour, ten grams are 
placed in a sieve containing a No. 10 bolting cloth ; with 
a camel's-hair brush and proper manipulation, the flour 
is sieved, and that which passes through is weighed. 
The percentage amount remaining on the No. 10 cloth 
is coarser middlings. Nearly all high-grade flours leave 
no residue on the No. 10 cloth. The sifted flour from 
the No. 10 cloth is also passed through Nos. 11, 12, 13, 
and 14 cloths.^^ In this way the approximate granula- 
tion of any grade of flour may be determined, and the 
granulation of an unknown sample be compared with 
that of a standard flour. In determining the granula- 
tion of a flour, if there are any coarse or discolored par- 
ticles of bran or dust, they should be noted, as it is an 
indication of poor milling. When the flour is smoothed 
with a trier, there should be no channels formed on the 
surface of the flour, due to fibrous impurities caught 
under the edge of the trier. A hand magnifying glass 
is useful for detecting the presence of abnormal 
amounts of dirt or fibrous matter in the flour. 

163. Capacity of Flour to absorb Water. — The ca- 
pacity of a flour to absorb water is determined by add- 
ing water from a burette to a weighed amount of flour 
until a dough of standard consistency is obtained. Low 
absorption is due to low gluten content. A good flour 
should absorb from 60 to 65 per cent of its weight of 



WHEAT FLOUR 151 

water. In making the test, it is advisable to determine 
the absorption of a flour of known baking value at 
the same time that an unknown flour is being tested. 
Flours of low absorption do not make breads of the best 
quality; also there are a smaller number of loaves per 
barrel, and the bread dries out more readily. 

164. Physical Properties of Gluten. — The percent- 
ages of wet and dry gluten in a flour are determined 
as outlined in Experiment No. 27. Flours of good 
character show at least 34 per cent of moist gluten and 
from II to 12 per cent of dry gluten. The quahty of 
a flour is not necessarily proportional to its gluten 
content, although a flour with less than io| per cent 
of dry gluten will not make the best quality of bread, 
and flours with excessive amounts are sometimes poor 
bread makers. The color of the gluten is also impor- 
tant ; it should be white or creamy. The statements 
made in regard to color of flour apply also to color of 
the gluten. A dark, stringy, or putty-Hke gluten is 
of little value for bread-making purposes.^"* In mak- 
ing the gluten test, it is advisable to compare the 
gluten with that from a flour of known bread-making 
value. Soft wheat flours have a gluten of different 
character from hard wheat flours. 

165. Gluten as a Factor in Bread Making. — The 

bread-making value of a flour is dependent upon the 
character of the wheat and the method of milling. It 



152 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

is not necessarily dependent upon the amount of 
gluten, as the largest volume and best quality of bread 
are often made from flour of average rather than maxi- 
mum gluten content. But flours with low gluten do 
not produce high-grade breads. When a flour con- 
tains more than 12 or 13 per cent of proteids, any in- 
crease does not necessarily mean added bread-making 
value. The quality of the gluten, equally with the 
amount, determines the value for bread-making pur- 
poses. 

168. Unsoundness. — A flour with more than 14 per 
cent of moisture is liable to become unsound. High 
acidity also is an indication of unsoundness or of 
poor keeping qualities. The odor of a sample of flour 
should always be carefully noted, for any suggestion 
of fermentation sufficient to affect the odor renders 
the flour unsuited for making the best bread. Any 
abnormal odor in flour is objectionable, as it is due to 
contamination of some sort, and most frequently to 
fermentation changes. A musty odor is always an 
indication of unsoundness. Some flours which have 
but a slight suggestion of mustiness will, when baked 
into bread, have it more pronounced; on the other 
hand, some odors are removed during bread making. 
Flours may absorb odors because of being stored in 
contaminated places or being shipped in cars in which 
oil or other ill-smelling products with strong odors 
have previously been shipped. Unsoundness is often 



WHEAT FLOUR 



153 



due to faulty methods in handling, as well as to poor 
wheat, or to lack of proper cleaning of the wheat or 
flour. 




Fig. 43. ~FuNc;(^us Growth in Unsound Flour. 



167. Comparative Baking Tests. — To determine the 
bread-making value of a flour, comparative baking 
tests, as outlined in Experiment No. 29,. are made ; 
the flour in question is thus compared as to bread- 



154 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

making value with a flour of known baking quality. 
In making the baking tests, the absorption of the 
flour, the way in which it responds in the doughing 
process, and the general properties of the dough, are 
noted. The details should be carried out with care. 




Fig. 44. — Comparative Bakix(; Tests. 

the comparison always being made with a similar flour 
of known baking value, and the bread should be baked 
at the same time and under the same conditions as the 
standard. The color of the bread, the size and weight 
of the loaf, and its texture and odor, are the principal 
characteristics to be noted. 

The quality of flour for bread-making purposes is not 



WHEAT FLOUR 1 55 

Strictly dependent upon any one factor, but appears to 
be the aggregate of a number of desirable character- 
istics. The commercial grade of a flour can be ac- 
curately determined from the color, granulation, absorp- 
tion, gluten and ash content, and the quality of the bread. 
Technical flour testing requires much experience and 
a high degree of skill. 

168. Bleaching. — In the process of manufacture, 
flours are often subjected to air containing traces of 
nitrogen peroxide gas, generated by electrical action 
and resulting in the union of the oxygen and nitrogen of 
the air. This whitens and improves the color of the 
flour. Bleached flours differ neither in chemical com- 
position nor in nutritive value from unbleached flours, 
except that bleached flours contain a small amount (about 
one part to one million parts of flour) of nitrite react- 
ing material, which is removed during the process of 
bread making. The amount of nitrites produced in 
flour during bleaching is less than is normally present 
in the saliva, or is found naturally in many vegetable 
foods, or in smoked or cured meats, or in bread made 
from unbleached flour and baked in a gas oven where 
nitrites are produced from combustion of the gas. 
The bleaching of flour cannot be regarded as in any 
way injurious to health or as adulteration, and a 
bleached flour which has good gluten and bread-making 
qualities is entirely satisfactory. It is not possible to 
successfully bleach low-grade flours so they will re- 



156 HUxMAN FOODS AND THEIR NUTRITIVE VALUE 

semble the high grades, because the bran impurities 
of the low grades blacken during bleaching and be- 
come more prominent. Alvvay, of the Nebraska Experi- 
ment Station, has shown that there is no danger to 
apprehend from over-bleaching, for when excess of 
the bleaching reagent is used, flours become yellow 
in color.*^^ Similar results have been obtained at the 
Minnesota Experiment Station. As bleaching is not 
injurious to health, and as it is not possible through 
bleaching to change low grades so as to resemble the 
patent grades, bleaching resolves itself entirely into the 
question of what color of flour the consumer desires. 



169. Adulteration of 

Flour. — Flour is not 
easily adulterated, as 
the addition of any for- 
eign material interferes 
with the expansion and 
bread-making qualities 
and hence is readily 
detected. The mixing 
of other cereals, as corn 
flour, with wheat flour 
has been attempted at 
various times when 
wheat commanded a 
high price, but this also is readily detected, by micro- 
scopic examination, as the corn starch and wheat 




Fig. 45. — Wheat Hairs and Debris 
IN Low Grade Flours. 



WHEAT FLOUR 157 

starch grains are quite different in mechanical struc- 
ture. Such flours are required to be labeled, in accord 
with the congressional act of 1898, when Congress 
passed, in advance of the general pure food bill, an 
act regulating the labehng and sale of mixed and 
adulterated flours. Various statements have been 
made in regard to the adulteration of flour with min- 
erals, as chalk and barytes, but such adulteration does 
not appear to be at all general. 

170. Nutritive Value of Flour. — From a nutritive 
point of view, wheat flour and wheat bread have a high 
value.^^ A larger amount of nutrients can be secured 
for a given sum of money in the form of flour than 
of any other food material except corn meal. Accord- 
ing to statistics, the average per capita consumption of 
wheat in the United States is about 4^ bushels, or, 
approximately, one barrel per year, and from recent 
investigations it would appear that the amount of flour 
used in the dietary is on the increase. According to 
the Bureau of Labor, flour costs the average laborer 
about one tenth as much as all other foods combined, 
although he secures from it a proportionally larger 
amount of nutritive material than from any other 
food. 



CHAPTER XI 
BREAD AND BREAD MAKING 

171. Leavened and Unleavened Bread. — To make 
unleavened bread the flour is moistened and worked 
into a stiff dough, which is then rolled thin, cut into 
various shapes, and baked, forming a brittle biscuit or 
cracker. 

The process of making raised or leavened bread con- 
sists, in brief, of mixing the flour and water in proper 
proportions for a stiff dough, together with some salt for 
seasoning, and yeast (or other agent) for leavening. The 
moistened gluten of the flour forms a viscid, elastic, 
tenacious mass, which is thoroughly kneaded to distrib- 
ute the yeast. The dough is then set in a warm place 
and the yeast begins to grow, or 'Svork," causing alco- 
holic fermentation, with the production of carbon dioxid 
gas, which expands the dough, or causes it to *' rise," 
thus rendering it porous. After the yeast has grown 
sufficiently, the dough is baked in a hot oven, where 
further fermentation is stopped because of destruction 
of the yeast by the heat, which also causes the gas to 
expand the loaf and, in addition, generates steam. The 
gas and steam inflate the tenacious dough and finally 

158 



BREAD AND BREAD MAKING 1 59 

escape into the oven. At the same time the gluten 
of the dough is hardened by the heat, and the mass 
remains porous and Hght, while the outer surface is 
darkened and formed into a crust. 

When the flour is of good quality, the dough well 
prepared, and the bread properly baked, the loaf has 
certain definite characteristics. It should be well raised 
and have a thin, flinty crust, which is not too dark in 
color nor too tough, but which cracks when broken ; the 
crumb, as the interior of the loaf is called, should be 
porous, elastic, and of uniform texture, without large 
holes, and should have good flavor, odor, and color. 

Meal or flour from any of the cereals may be used for 
unleavened bread, but leavened bread can be made only 
from those that contain gluten, a mixture of vegetable 
proteids which when moistened with water becomes 
viscid, and is tenacious enough to confine the gas pro- 
duced in the dough. Most cereals, as barley, rice, oats, 
and corn, some of which are very frequently made into 
forms of unleavened bread, are deficient or wholly lack- 
ing in gluten, and hence cannot be used alone for 
making leavened bread. For the leavened bread, wheat 
and rye, which contain an abundance of gluten, are 
best fitted, wheat being in this country by far the more 
commonly used. 

172. Changes during Bread Making. — In bread mak- 
ing complex physical, chemical, and biological changes 
occur. Each chemical compound of the flour undergoes 



l6o HUMAN FOODS AND THEIR NUTRITIVE VALUE 

some change during the process. The most important 
changes are as follows : ^* 

1. Production of carbon dioxid gas, alcohol, and solu- 
ble carbohydrates as the result of ferment action. 

2. Partial rupturing of the starch grains and forma- 
tion of a small amount of soluble carbohydrates due to 
the action of heat. 

3. Production of lactic and other organic acids. 

4. Formation of volatile carbon compounds, other 
than alcohol and carbon dioxid. 

5. Change in the solubility of the gluten proteins, due 
to the action of the organic acids and fermentation. 

6. Changes in the solubility of the proteids due to 
the action of heat, as coagulation of the albumin and 
globulin. 

7. Formation and liberation of a small amount of 
volatile, nitrogenous compounds, as ammonia and amids. 

8. Partial oxidation of the fat. 

173. Loss of Dry Matter during Bread Making. — As 

many of the compounds formed during bread making 
are gases resulting from fermentation action, and as 
these are volatile at the temperature of baking, appreci- 
able losses necessarily take place. Experiments show 
about 2 per cent of loss of dry matter under ordinary 
conditions. These losses are not confined to the carbo- 
hydrates alone, but also extend to the proteids and other 
compounds. When 100 pounds of flour containing lO 
per cent of water and 90 per cent of dry matter are 



BREAD AND BREAD MAKING l6l 

made into bread, the bread contains about 88 pounds of 
dry matter. In exceptional cases, where there has been 
prolonged fermentation, the losses exceed 2 per cent.*"^ 




Fig. 46.— Brewers' Yeast. 

174. Action of Yeast. — Yeast is a monocellular plant 
requiring sugar and other food materials for its nourish- 
ment. Under favorable conditions it rapidly increases 
by budding, and as a result produces the well-known 
alcoholic fermentation. It requires mineral food, as do 
plants of a higher order, and oftentimes the fermenta- 
tion process is checked for want of sufficient soluble 



l62 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

mineral food. The yeast plant causes a number of 
chemical changes to take place, as conversion of starch 
to a soluble form and alcoholic fermentation. 

QHj^.Og + H2O = CgHi20e. 

^6^1206 = 2 C2H5OH + 2 CO2. 

Alcoholic fermentation cannot occur until the starch has 
been converted into dextrose sugar. The yeast plant is 
destroyed at a temperature of 131^ F. It is most active 
from 70° to 90° F. At a low temperature it is less active, 
and when it freezes the cells are ruptured. A number 
of different kinds of fermentation are associated with the 
growth of the yeast plant, and there are many varieties 
of yeast, some of which are more active than others. 
For bread making an active yeast is desirable to prevent 
the formation of acid bodies. If the work proceeds 
quickly, the rising process is completed before the 
acid fermentation is far advanced. If fermentation is 
too prolonged, some of the products of the yeast plant 
impart an undesirable taste and odor to the bread, and 
hinder the development of the gluten and expansion of 
the loaf. 

175. Compressed Yeast. — The yeast most commonly 
used in bread making is compressed yeast, a product of 
distilleries. The yeast floating on the surface of the 
wort is skimmed off and that remaining is allowed to 
settle to the bottom, and is obtained by running the wort 
into shallow tanks or settling trays. It is then washed 



BREAD AND BREAD MAKING 1 63 

with cold water, and the impurities are removed either 
by sieving through silk or wire sieves, or, during the 
washing, by fractional precipitation. The yeast is then 
pressed, cut into cakes, and wrapped in tinfoil. When 
fresh, it is of uniform creamy color, moist, and of a firm, 
even texture. ^^ It should be kept cold, as it readily de- 
composes. 

176. Dry Yeast is made by mixing starch or meal 
with fresh yeast until a stiff dough is formed. This is 
then dried, either in the sun or at a moderate tempera- 
ture, and cut into cakes. By drying, many of the yeast 
cells are rendered temporarily inactive, and so it is a 
slower acting leaven than the compressed yeast. A dry 
yeast will keep indefinitely. 

177. Production of Carbon Dioxid Gas and Alcohol. — 
Carbon dioxid and alcohol are produced in the largest 
amounts of any of the compounds formed during bread 
making. When the alcoholic ferments secreted by the 
yeast plant act upon the invert sugars and produce 
alcoholic fermentation, carbon dioxid is one of the prod- 
ucts formed. Ordinarily about i per cent of carbon 
dioxid gas is generated and lost during bread making. 
About equal weights of carbon dioxid and alcohol are 
produced during the fermentation. In baking, the al- 
cohol is vaporized and aids the carbon dioxid in expand- 
ing the dough and making the bread porous. If all of 
the moisture given off during bread making be collected 
it will be found that from a pound loaf of bread there 



164 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

are about 40 cubic centimeters of liquid ; when this is 
submitted to chemical analysis, small amounts of alcohol 
are obtained. Alcoholic fermentation sometimes fails 
to take place readily, because there are not sufficient 
soluble carbohydrates to undergo inversion, or other 
food for the yeast plant. Starch cannot be converted 
directly into alcohol and carbon dioxid gas ; it must 




Fig. 47. — Wheat Starch Granules after Fermentation with 
Yeast, as in Bread Making. 

first be changed into dextrose sugars, and these undergo 
alcoholic fermentation. Bread gives no appreciable 
reaction for alcohol even when fresh.^* 

If the gluten is of poor quality, or deficient in either 
gliadin or glutenin, the dough mass fails to properly 
expand because the gas is not all retained. The amount 
of gas formed is dependent upon temperature, rapidity 
of the ferment action, and quality of the yeast and flour. 
If the yeast is inactive, other forms of .fermentation than 



BREAD AND BREAD MAKING 165 

the alcoholic may take place and, as a result, the dough 
does not expand. Poor yeast is a frequent cause of poor 
bread. 

The temperature reached in bread making is not 
sufficient to destroy all the ferment bodies associated 
with the yeast, as, for example, bread sometimes be- 
comes soft and stringy, due to fermentation changes 
after the bread has been baked and stored. Both bread 
and flour are subject to many bacterial diseases, and 
one of the objects of thorough cleaning of the wheat 
and removal of the bran and debris particles during the 
process of flour manufacture is to completely eliminate 
all ferment bodies mechanically associated with the 
exterior of the wheat kernel, which, if retained in the 
flour, would cause it readily to become unsound. 

178. Production of Soluble Carbohydrates. — Flour 
contains naturally a small amount of soluble carbohy- 
drates, which are readily acted upon by the alcoholic 
ferments. The yeast plant secretes soluble ferments, 
which act upon the starch, forming soluble carbohydrates, 
and the heat during baking brings about similar changes. 
In fact, soluble carbohydrates are both consumed and 
produced by ferment action during the bread-making 
process. Flour contains, on an average, 65 per cent of 
starch, and during bread making about 10 per cent is 
changed to soluble forms. Bread, on a dry matter basis, 
contains approximately 6 per cent of soluble carbohy- 
drates, including dextrine, dextrose, and sucrose sugars.*"^ 



l66 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

The physical changes which the starch grains undergo 
are also noticeable. Wheat starch has the structure 
shown in illustration No. 33. The starch grains are 
circular bodies, concave, with slight markings in the 
form of concentric rings. When the proteid matter of 
bread is extracted with alcohol and the starch grains 
are examined, it will be seen that some of them are 
partially ruptured, hke those in popped corn, while 
others have been slightly acted upon or eaten away by 
the organized ferments, the surface of the starch grains 
being pitted, as shown in the illustration. The, joint 
action of heat and ferments on the starch grains changes 
them physically so they may more readily undergo 
digestion. The brown coating or crust formed upon the 
surface of bread is mainly dextrine, produced by the 
action of heat on the starch. Dextrine is a soluble car- 
bohydrate, having the same general composition as 
starch, but differing from it in physical properties and 
ease of digestion. 

179. Production of Acids in Bread Making. — Wheat 
bread made with yeast gives an acid reaction. The 
acid is produced from the carbohydrates by ferment 
action. Flour contains about one tenth of i per cent 
of acid; the dough contains from 0.3 to 0.5 per cent, 
while the baked bread contains from o. 14 to 0.3 per cent, 
but after two or three days slightly more acid is devel- 
oped.^* During the process of bread making, a small 
portion of the acid is volatilized, but the larger part 



BREAD AND BREAD MAKING 167 

enters into chemical combination with the gliadin, form- 
ing an acid proteid. When the alcoholic fermentation 
of bread making becomes less active, acid fermentations 
begin, and sour dough results. It is not definitely 
known what specific organic acids are developed in 
bread making. Lactic and butyric acids are known to 
be formed, and for purposes of calculation, the total 
acidity is expressed in terms of lactic acid. 

The acidity is determined by weighing 20 grams of 
flour into a flask, adding 200 cubic centimeters of 
distilled water, shaking vigorously, and leaving the 
flour in contact with the water for an hour; 50 cubic 
centimeters of the filtered solution are then titrated with a 
tenth normal solution of potassium hydroxid. Phenol- 
phthalein is used as the indicator. It cannot be said 
that all of the alkali is used for neutralizing the acid, 
as a portion enters into chemical combination with the 
proteids. If the method for determining the acid be 
varied, constant results are not secured. Unsound 
or musty flours usually show a high per cent of acidity. 

180. Volatile Compounds produced during Bread Mak- 
ing. — In addition to carbon dioxid and alcohol, there 
is lost during bread making a small amount of carbon 
in other forms, as volatile acids and hydrocarbon 
products equivalent to about one tenth of one per cent 
of carbon dioxid. The aroma of freshly baked bread 
is due to these compounds. Both the odor and 
flavor of bread are caused in part by the volatile acids 



l68 HUMAN FOODS AND THEIR NUTRITIVE VALUE 



and hydrocarbons. The amount and kind of volatile 
products formed can be somewhat regulated through 
the fermentation process by the use of special flours 
and the addition of materials that produce specific 
fermentation changes and desirable aromatic com- 
pounds. Some of the ferment bodies left in flour from 




Fig. 48. — Apparatus used in Study of Losses in Bread Making, 

the imperfect removal of the dirt adhering to the ex- 
terior of the wheat kernels impart characteristic 
flavors to the bread. The so-called nutty flavor of 
some bread is due to the action of these ferment 
bodies and, when intensified, it becomes objectionable. 
Fungous growths in unsound flour and bread result 
in the liberation of volatile products, which impart a 
musty odor. Good odor and flavor are very desirable 
in both flour and bread. 



BREAD AND BREAD MAKING 1 69 

181. Behavior of Wheat Proteids in Bread Making. — 

Gluten is an ingredient of the flour on which its bread- 
making properties largely depend. The important 
thing, however, is not entirely the quantity of gluten, 
but more particularly its character. Two flours 
containing the same amounts of carbohydrates and 
proteid compounds, when converted into bread by 
exactly the same process, may produce bread of entirely 
different physical characteristics because of differences 
in the nature of the gluten of the two samples. Gluten 
is composed of two bodies called gliadin and glutenin. 
The gliadin, a sort of plant gelatin, is the material 
which binds the flour particles together to form the 
dough, thus giving it tenacity and adhesiveness ; and 
the glutenin is the material to which the gliadin 
adheres. If there is an excess of gliadin, the dough is 
soft and sticky, while if there is a deficiency, it lacks 
expansive power. Many flours containing a large 
amount of gluten and total proteid material and 
possessing a high nutritive value, do not yield bread 
of the best quality, because of an imperfect blending 
of the gliadin and glutenin. This question is of much 
importance in the milling of wheats, especially in the 
blending of the different types of wheat. An abnor- 
mally large amount of gluten does not yield a corre- 
spondingly large loaf. 

Experiments were made at the Minnesota Experiment 
Station to determine the relation between the nature 
of the gluten and the character of the bread. This was 



lyo HUMAN FOODS AND THEIR NUTRITIVE VALUE 

done by comparing bread from normal flour with 
that from other flour of the same lot, but having part 
or all of its gliadin extracted.*^* Dough made from the 
latter was not sticky, but felt like putty, and broke 




Fig. 49.— Bread from Normal Flour (i) ; Gliadin Extracted Flour 
(2) ; and from Flour after Extraction of Sugar and Soluble 
Proteids (3). 



in the same way. The yeast caused the mass to 
expand a little when first placed in the oven ; then 
the loaf broke apart at the top and decreased in size. 
When baked it was less than half the size of that 
from the same weight of normal flour, and decidedly 
inferior in other respects. The removal of part of 



BREAD AND BREAD MAKING 17I 

the gliadin produced nearly the same effect as the 
extraction of the whole of it, and even when an equal 
quantity of normal flour was mixed with that from 
which part of the ghadin had been extracted, the 
bread was only sHghtly improved. In flour of the 
highest bread-making properties the two constituents, 
gliadin and glutenin, are present in such proportions 
as to form a well-balanced gluten. 

The proteids of wheat flour are mainly in an in- 
soluble form, although there are small amounts of 
albumins and globuHns ; these are coagulated by the 
action of heat during the bread-making process, and 
rendered insoluble. A portion of the acid that is 
developed unites with the gliadin and glutenin, forming 
acid proteids, which change the physical properties 
of the dough. Both gliadin and glutenin take im- 
portant parts in bread making. The removal of ghadin 
from flour causes complete loss of bread-making 
properties. Ordinarily from 45 to 65 per cent of 
the total nitrogen of the flour is present in alcohol 
soluble or gliadin form. Proteids also undergo hy- 
dration during mixing, some water being chemically 
united with them, changing their physical properties. 
This hydration change is necessary for the full de- 
velopment of the physical properties of the gluten. 
The water and salt soluble proteids appear to take 
no important part in the bread-making process, as 
their removal in no way affects the size of the loaf 
or general character of the bread. Because of the 



172 HUMAN FOODS ANDTHEIR NUTRITIVE VALUE 

action of the acids upon the gliadin, bread contains 
a larger amount of alcohol soluble nitrogen or gliadin 
than the flour from which the bread was made. It 
is believed that this action changes the molecular 
structure of the protein so that it is more readily 
separated into its component parts when it undergoes 
digestion and assimilation. 

182. Production of Volatile Nitrogenous Compounds. 

— When fermentation is unnecessarily prolonged, an 
appreciable amount of nitrogen is volatilized in the 
form of ammonia and allied bodies, as amids. During 
the process of bread making, the yeast appears to act 
upon the protein, as well as upon the carbohydrates, 
and, as previously stated, losses of dry matter fall 
alike upon these two classes of compounds, nitrogenous 
and non-nitrogenous. Analyses of the flours and 
materials used in bread making, and of the bread, show 
that ordinarily about 1.5 per cent of the total nitrogen 
is hberated in the form of gas during the bread-mak- 
ing process, and analyses of the gases dispelled in 
baking show approximately the same per cent of 
nitrogen. When bread is dried, as in a drying oven, 
a small amount of volatile nitrogen appears to be 
given off, — probably as ammonium compounds formed 
during fermentation. The nitrogen lost in bread mak- 
ing under ordinary conditions is not sufficient to affect 
the nutritive value of the product. The losses of both 
nitrogen and carbon are more than offset by the in- 



BREAD AND BREAD MAKING 1 73 

creased solubility of the proteids and carbohydrates, 
the preliminary changes they have undergone making 
them more digestible and valuable for food purposes. 
The nitrogen volatilized in bread making appears to 
be mainly that present in the flour in amid forms or 
liberated as the result of fermentation processes. The 
more stable proteids undergo only limited changes in 
solubiHty and are not volatilized. 

183. Oxidation of Fat. — Flour contains about 1.25 
per cent of fat mechanically mixed with a small amount 
of yellow coloring matter. During the process of bread 
making the fat undergoes slight oxidation, accompanied 
by changes in both physical and chemical properties. 
The fat from bread, when no lard or shortening has been 
added, is darker in color, more viscous, less soluble in 
ether, and has a lower iodine number, than fat from 
flour. The change in solubility of the fat is not, how- 
ever, such as to affect food value, because the fat is not 
volatilized, and is only changed by the addition of a 
small amount of oxygen from the air. When wheat fat 
and other vegetable and animal fats are exposed to the 
air, they undergo changes known as aging, similar to 
the slight oxidation changes in bread making.^^ 

184. Influence of the Addition of Wheat Starch and 
Gluten to Flour. —Ten per cent or more of starch may 
be added to normal flour containing a well-balanced 
gluten, without decreasing the size of the loaf. When 
moist gluten was added to flour, thus increasing the 



174 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

total amount of gluten, the size of the loaf was not 
increased.*^" 



Influence of Addition of Starch and Gluten to Flour 





Size of Loaf 


Weight 


Wheat flour, 


14 ounces 


221 X 171 


18,75 


Wheat flour, 


10 7o wheat starch .... 


23i X 17 


18.25 


Wheat flour, 


12.2 % wheat starch .... 


211 X 17 


18.00 


Wheat flour. 


210 grams, about 8 ounces . . 


I2f X 9 


12.00 


Wheat flour. 


10 % gluten added, 210 grams . 


121 X 9 


12.75 


Wheat flour. 


20 % gluten added .... 


12 X 8| 


13.00 



So long as the quality of the gluten is not destroyed, 
the addition of a small amount of either starch or gluten 
to flour does not affect the size of the loaf, but removal 
of the gluten affects the moisture content and physical 
properties of the bread. The addition of starch to flour 
has the same effect upon the bread as the use of low 
gluten flour, — lessening the capacity of the flour to 
absorb water and producing a dryer bread of poorer 
quality. 



185. Composition of Bread. — The composition of bread 
depends primarily upon that of the flour from which it 
was made. If milk and butter (or lard) are used in mak- 
ing the dough, as is commonly the case, their nutrients 
are, of course, added to those of the flour; but when 
only water and Hour are used, thj nutrients of the bread 



BREAD AND BREAD MAKING 



17. 



are simply those of the flour. In either case the amount 
of nutrients in the bread is smaller than in the same 
weight of flour, because a considerable part of the 
water or milk used in making the dough is present in the 
bread after baking ; that is, a pound of bread contains less 
of any of the nutrients than a pound of the flour from 
which the bread was made, because the proportion of 
water in the bread is greater. The following table shows 
how the composition of flour compares with that of bread, 
the different kinds of bread all having been made from 
the flour with which they are compared : 

Composition of Flour, and Bread made from it in 
Different Ways 



Material 


Water 


Protein 


Fat 


C.H. 


Ash 


Flour 

Bread from flour and water . . 
Bread from flour, water, and lard 
Bread from flour and skim milk 


% 
10. II 
36.12 
37.70 
36.02 


% 

12.47 
9.46 
9.27 

10.57 


% % 

0.86 76.09 
0.40 53.70 
1.02 51.70 
0.48 52.63 


% 

0.47 
0.32 
0.31 
0.30 



Thus it may be seen that the proportion of water is 
larger and of each nutrient smaller in bread than in 
flour, and that the nutrients of the flour are in- 
creased by those in the materials added in making the 
bread. 

It is apparent that two breads of the same lot of flour 
may differ, according to the method used in making, 



176 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

and also that two loaves of bread made by exactly the 
same process but from different lots of flour, even when 
of the same grade or brand, do not necessarily have the 
same composition, because of possible variation in the 
flours. In bread made from flour of low gluten content, 
the per cent of protein is correspondingly low. 

186. Use of Skim Milk and Lard in Bread Making. — 

When flours low in gluten are used, skim milk may be 
employed advantageously in making the bread, to increase 
the protein content. Tests show that such bread contains 
about I per cent more protein than that made with 
water. Ordinarily there is no gain from a nutritive 
point of view in adding an excessive amount of lard or 
other shortening, as it tends to widen the nutritive 
ratio. 

187. Influence of Warm and Cold Flours on Bread 
Making. — When flour is stored in a cold closet or store- 
room, it is not in condition to produce a good quality of 
bread until it has been warmed to a temperature of about 
70° F. Cold flour checks the fermentation process, and 
is occasionally the cause of poor bread. On the other 
hand, when flour is too warm (98° F.) the influence upon 
fermentation is unfavorable. Heating of flour does not 
affect the bread-making value, provided the flour is not 
heated above 158° F. and is subsequently cooled to a 
temperature of 70°. Wheat flour contains naturally a 
number of ferment substances, some of which are de- 



BREAD AND BREAD MAKING 



n 



stroyed by the action of heat. The natural ferments, or 
enzymes, of flour appear to take a part in bread making, 
imparting characteristic odors and flavors to the prod- 
uct. 

188. Variations in the Process of Bread Making. — 

Since flours differ so in chemical composition, and the 




Fig. 50. — Bread from (i) Graham, (2) Entire Wheat, and 
(3) White Flour. 

The same amounts of flour were used in making all of the breads. 



yeast plant acts upon all the compounds of flour, it natu- 
rally follows that bread making is not a simple but a 
complex operation, resulting in a number of intricate 
chemical reactions, which it is necessary to control and 
many of which are only imperfectly understood. Bread 



178 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

of the best physical quahty and commercial value is 
made of flour from fully matured, hard wheats, contain- 
ing" a low per cent of acid, no foreign ferment materials 
or their products, and at least I2| per cent of pro- 
teids, of which the larger portion is in the form of 
gliadin. It is believed that a better quality of bread 
could be produced from many flours by slight changes 
or modifications in the process of bread making. It can- 
not be expected that the same process will give the best 
results alike with all types and kinds of flour. The kind 
of fermentation process that will produce the best bread 
from a given type of flour can be determined only by 
experimentation. Poor bread making is due as often to 
lack of skill on the part of the bread maker, and to poor 
yeast, as it is to poor quality of flour. Frequently the 
flour is blamed when the poor bread is due to other fac- 
tors. Lack of control of the fermentation process, and 
the consequent development of acid and other organisms 
which check the activity of the alcoholic ferments, is a 
frequent cause of poor bread. 

189. Digestibility of Bread. — Extensive experiments 
have been made by the Office of Experiment Stations of 
the United States Department of Agriculture, at the 
Minnesota and Maine Experiment Stations, to determine 
the digestibiUty and nutritive value of bread. Different 
kinds and types of wheat were milled so as to secure 
from each three flours : graham, entire wheat, and stand- 
ard patent. The flours were made into bread, and the 



BREAD AND BREAD MAKING 1 79 

bread fed to workingmen, and its digestibility deter- 
mined. The experiments taken as a whole show that 
bread is an exceedingly digestible food, nearly 98 per 
cent of the starch or carbohydrate nutrients and about 
88 per cent of the gluten or proteid constituents being 
assimilated by the body. In the case of the graham and 
entire wheat flours, although they contained a larger 
total amount of protein, the nutrients were not as com- 
pletely digested and absorbed by the body as were those 
of the white flour. The body secured a larger amount 
of nutrients from the white than from the other grades 
of flour, the digestibility of the three types being as fol- 
lows : standard patent flour, protein 88.6 per cent and 
carbohydrates 97.7 per cent; entire wheat flour, protein 
82 percent and carbohydrates 93.5 per cent; graham 
flour, protein 74.9 per cent and carbohydrates 89.2 per 
cent. The low digestibility of the protein of the graham 
and entire wheat flours is supposed to be due to the 
coarser granulation ; the proteins, being embedded and 
surrounded with cellular tissue, escape the action of the 
digestive fluids. Microscopic examination of the feces 
showed that often entire starch grains were still inclosed 
in the woody coverings and consequently had failed to 
undergo digestion. ^2,64,67,86 

190. Use of Graham and Entire Wheat in the Dietary. 

— Entire wheat and graham flours should be included 
in the dietary of some persons, as they are often valu- 
able because of their physiological action, the branny 



l8o HUMAN FOODS AND THEIR NUTRITIVE VALUE 

particles stimulating the process of digestion and en- 
couraging peristaltic action. In the diet of the overfed, 
they are valuable for the smaller rather than the larger 
amount of nutrients they contain. Also they supply 
bulk and give the digestive tract needed exercise. For 
the laboring man, where it is necessary to obtain the 
largest amount of available nutrients, bread from white 
flour should be suppUed ; in the dietary of the sedentary, 
graham and entire wheat flours can, if found beneficial, 
be made to form an essential part. The kind of bread 
that it is best to use is largely a matter of personal choice 
founded upon experience. 

'"When we pass on to consider the relative nutritive values of 
white and whole-meal bread, we are on ground that has been the 
scene of many a controversy. It is often contended that whole-meal 
is preferable to white bread, because it is richer in proteid and 
mineral matter, and so makes a better balanced diet. But our ex- 
amination of the chemical composition of whole-meal bread has shown 
that as regards proteid at least, this is not always true, and even 
were it the case, the lesser absorption of whole-meal bread, which we 
have seen to occur, would tend to annul the advantage. . . . On the 
whole, we may fairly regard the vexed question of whole-meal versus 
white bread as finally settled and settled in favor of the latter."" '•^^ 

'• The higher percentage of nitrogen in bran than in fine flour has 
frequently led to the recommendation of the coarser breads as more 
nutritious than the finer. We have already seen that the more 
branny portions of the grain also contain a much larger percentage 
of mineral matter. And, further, it is in the bran that the largest 
proportion of fatty matter — the non-nitrogenous substance of higher 
respiratory capacity which the wheat contains — is found. It is, 
however, we think, very questionable whether upon such data alone 



BREAD AND BREAD MAKING l8l 

a valid opinion can be formed of the comparative values of bread 
made from the finer or coarser flours ground from one and the same 
grain. Again, it is an indisputable fact that branny particles when 
admitted into the flour in the degree of imperfect division in which 
our ordinary milling processes leave them very considerably increase 
the peristaltic action, and hence the alimentary canal is cleared much 
more rapidly of its contents. It is also well known that the poorer 
classes almost invariably prefer the whiter bread, and among some 
of those who work the hardest and who consequently soonest appre- 
ciate a difference in nutritive quality (navvies, for example) it is 
distinctly stated that their preference for the whiter bread is founded 
on tlie fact that the browner passes through them too rapidly ; con- 
sequently, before their systems have extracted from it as much 
nutritious matter as it ought to yield them. ... In fact, all experi- 
ence tends to show that the state as well as the chemical composi- 
tion of our food must be considered ; in other words, that the 
digestibility and aptitude for assimilation are not less important 
qualities than its ultimate composition. 

'• But to suppose that whole-wheat meal as ordinarily prepared is, 
as has generally been assumed, weight for weight more nutritious 
than ordinary bread flour is an utter fallacy founded on theoretical 
text-book dicta, not only entirely unsupported by experience, but in- 
consistent with it. In fact, it is just the poorer fed and the harder 
working that should have the ordinary flour bread rather than the 
whole-meal bread as hitherto prepared, and it is the overfed and 
the sedentary that should have such whole-meal bread. Lastly, if the 
whole grain were finely ground, it is by no means certain that the 
percentage of really nutritive nitrogenous matters would be higher 
than in ordinary bread flour, and it is quite a question whether 
the excess of earthy phosphates would not then be injurious." 
— Lawes and Gilbert.^s 

" According to the chemical analysis of graham, entire wheat, and 
standard patent flours milled from the same lot of hard Scotch Fife 
spring wheat, the graham flour contained the highest and the patent 



1 82 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

flour the lowest percentage of total protein. But according to the 
results of digestion experiments with these flours the proportions of 
digestible or available protein and available energy in the patent flour 
were larger than in either the entire wheat or the graham flour. The 
lower digestibility of the protein of the latter is due to the fact that 
in both these flours a considerable portion of this constituent is con- 
tained in the coarser particles (bran), and so resists the action of the 
digestive juices and escapes digestion. Thus while there actually 
may be more protein in a given amount of graham or entire wheat 
flour than in the same weight of patent flour from the same wheat, 
the body obtains less of the protein and energy from the coarse flour 
than it does from the fine, because, although the including of the 
bran and germ increases the percentage of protein, it decreases its 
digestibility. By digestibility is meant the difference between the 
amounts of the several nutrients consumed and the amount excreted 
in the feces. 

'• The digestibility of first and second patent flours was not appre- 
ciably diff"erent from that of standard patent flour. The degree 
of digestibility of all these flours is high, due largely to their mechan- 
ical condition ; that is, to the fact that they are finely ground." — 
Snyder. 6- 

For a more extended discussion of the subject, the 
student is referred to Bulletins 6j, lOi, and 126, Office 
of Experiment Stations, United States Department of 
Agriculture. 

191. Mineral Content of White Bread. — Average flour 
contains from 0.4 to 0.5 of i per cent of ash or mineral 
matter, the larger portion being lime and magnesia and 
phosphate of potassium. It is argued by some that 
graham and entire wheat flours should be used liberally 
because of their larger mineral content and their greater 



BREAD AND BREAD MAKING 183 

richness in phosphates. In a mixed dietary, however, 
in which bread forms an essential part, there is always 
an excess of phosphates, and there is nothing to be gained 
by increasing the amount, as it only requires additional 
work of the kidneys for its removal. Few experiments 
have been made to determine the phosphorus require- 
ments of the human body, but these indicate that it is 
unnecessary to increase the phosphate content of a 
mixed diet. It is estimated that less than two grams per 
day of phosphates are required to meet all of the needs 
of the body, and in an average mixed ration there are 
present from three to five grams and more. A large 
portion of the phosphate compounds of white bread is 
present in organic combinations, as lecithin and nucleated 
proteids, which are the most available forms, and more 
valuable for purposes of nutrition than the mineral 
phosphates. In the case of graham and entire wheat 
flours, a proportionally smaller amount of the phos- 
phates are digested and assimilated than from the finer 
grades of flour. 

192. Comparative Digestibility of New and Old Bread. 

— With healthy persons there is no difference whatever 
in the completeness of digestibility of old and new 
bread ; one appears to be as thoroughly absorbed as the 
other. In the case of some individuals with impaired 
digestion there may be a difference in the ease and com- 
fort with which the two kinds of bread are digested, but 
this is due mainly to individuahty and does not apply 



184 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

generally. The change which bread undergoes when it 
is kept for several days is largely a loss of moisture and 
development of a small amount of acid and other sub- 
stances from the continued ferment action. 

193. Different Kinds of Bread. — According to varia- 
tions in method of preparation, there are different types 
and varieties of bread, as the ''flat bread" of Scandi- 
navian countries, unleavened bread, Vienna bread, salt 
rising bread, etc. Bread made with baking powder 
differs in no essential way from that made with yeast, 
except in the presence of the residue from the baking 
powder, discussed in Chapter XII. Biscuits, wheat 
cakes, crackers, and other food materials made princi- 
pally from flour, have practically the same food value as 
bread. It makes but little difference in what way flour 
is prepared as food, for in its various forms it has 
practically the same digestibility and nutritive value. 

194. Toast. — When bread is toasted there is no 
change in the percentage of total nutrients on a dry 
matter basis. The change is in solubiHty and form, and 
not in amount of nutrients available. Some of the starch 
becomes dextrine, which is more soluble and digestible.^ 
Proteids, on the other hand, are rendered less soluble, 
which appears to slightly lower the digestion coefficient. 
They are somewhat more readily but not quite so com- 
pletely digested as those of bread. Digestion experi- 
ments show that toast more readily yields to the diastase 
and other ferments than does wheat bread. Toasting 



BREAD AND BREAD MAKING 1 85 

brings about ease of digestion rather than increased 
completeness of the process. Toast is a sterile food, 
while bread often contains various ferments which have 
not been destroyed by baking. These undergo incuba- 
tion during the process of digestion, particularly in the 
case of individuals with diseases of the digestive tract. 
With normal digestion, however, these ferment bodies 
do not develop to any appreciable extent, as the digestive 
tract disinfects itself. When the flour is prepared from 
well cleaned wheat and the ferment substances which 
are present mainly in the bran particles have been re- 
moved, a flour of higher sanitary value is secured. 



CHAPTER XII 
BAKING POWDERS 

195. General Composition. — All baking powders con- 
tain at least two materials ; one of these has combined 
carbon dioxid in its composition, the other some acid 
constituent which serves to liberate the gas. The ma- 
terial from which the gas is obtained is almost invaria- 
,bly sodium bicarbonate, NaHCOg, commonly known as 
*' soda " or '* saleratus." Ammonium carbonate has been 
used to some extent, but is very seldom used at the 
present time. The acid constituent may be one of sev- 
eral materials, the most common being cream of tartar, 
tartaric acid, calcium phosphate, or alum. These may be 
used separately or in combination. The various baking 
powders are designated according to the acid constituent, 
as "cream of tartar," ''phosphate," and *' alum " powders. 
All of them liberate carbon dioxid gas, but the products 
left in the food differ widely in nature and amount.^^ 

Baking powder is a chemical preparation which, 
when brought in contact with water, liberates carbon 
dioxid gas. The baking powder is mixed dry with 
flour, and when this is moistened the carbon dioxid 
that is liberated expands the dough. The action is simi- 

i86 



BAKING POWDERS 



187 



lar to that of yeast except that in the case of yeast the 
gas is given off much more slowly and no residue is left 
in the bread. When baking powder is used, there is a 
residue left in the food which varies with the material 
in the powder. It is the nature and amount of this resi- 



- -^^^^ 





1234 

Fig. 51. — Ingredients of a Baking Powder. 

I, baking powder; 2, cream of tartar; 3, baking soda; 4, starch. 



due that is important and makes one baking powder 
more desirable than another. 

196. Cream of Tartar Powders. — The acid ingredient 
of the cream of tartar powders is tartaric acid, Hfi^HfiQ. 
Cream of tartar is potassium acid tartrate, KHC^H^Og; 
it contains one atom of replaceable hydrogen, which im- 
parts the acid properties, and it is prepared from crude 



1 88 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

argol, a deposit of grape juice when wine is made. The 
residue from this powder is sodium potassium tartrate, 
NaKQH^Og, commonly known as Rochelle salt. This 
is the active ingredient of Seidlitz powders and has a 
purgative effect when taken into the body. The dose 
as a purgative is from one half to one ounce. A loaf of 
bread as ordinarily made with cream of tartar powder 
contains about i6o grains of Rochelle salt, which is 45 
grains more than is found in a Seidlitz powder, but the 
amount actually eaten at any one time is small and its 
physiological effect can probably be disregarded. When 
a cream of tartar baking powder is used, the reaction 
takes place according to the following equation : 

188 84 210 44 18 

HKH^C^Og + NaHCOg = KNaC^H^O^ + CO2 + Hfi. 

The crystallized Rochelle salt contains four molecules 
of water, so that, even allowing for some starch filler, 
there is very nearly as much weight of material (Ro- 
chelle salt) left in the food as there was of the original 
powder. If free tartaric acid were used instead of 
potassium acid tartrate, the reaction would be as follows : 

H2C4H4O6 + 2 NaHCOg = Na2CjH^0, • 2 H2O + 2 CO2. 

But the residue, sodium tartrate, is less in proportion. 
It has physiological properties very similar to Rochelle 
salt. Tartaric acid is seldom used alone, but very often 
in combination with cream of tartar. It is more expen- 
sive than cream of tartar ; but not so much is required, 
and it is more rapid in action. 



BAKING POWDERS 1 89 

197. Phosphate Baking Powders. — Here the acid 
ingredient is phosphoric acid and the compound usually 
employed is mono-calcium phosphate, CaH^ (P04)2. 
This is made by the action of sulphuric acid on ground 
bone (CagCPO J.3 + 2 H^SO^ = CaH4(PO J2 + 2 CaSO^), 
and it is difficult to free it from the calcium phosphate 
formed at the same time ; hence such powders contain 
more or less of this inert material. The reaction which 
occurs with a phosphate powder is as follows : 

CaH4(POj2 + 2 NaHCOg = CaHPO^ 

88 36 142 

+ 2 CO2 + 2 H2O -f Na2HPO^. 

Sodium phosphate, according to the United States 
Dispensatory, is ''mildly purgative in doses of from i 
to 2 ounces." The claim is made by the makers of 
phosphate baking powders that the phosphates of so- 
dium and calcium, products left after the baking, re- 
store the phosphates which have been lost from the 
flour in the bran. This baking powder residue does 
not restore the phosphates in the same form in which 
they are present in grains and it does furnish them in 
larger amounts — nearly tenfold. However, the resi- 
due from these powders is probably less objectionable 
than that from alum powders. The chief drawback to 
the phosphate powders is their poor keeping quaHties. 

198. Alum Baking Powders. — Sulphuric acid is the 
acid constituent of these powders. The alums are double 



190 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

sulphates of aluminium and an alkali metal, and have the 
general formula ;i'Al(S04)2 in which x may be K, Na, 
or NH4, producing respectively a potash, soda, or 
ammonia alum. Potash alum is most commonly used, 
soda and ammonia alums to a less extent. The reac- 
tion takes place as follows : 

475 504 157 

2 NH^AKSOJ., + 6 NaHCOs = AyOH)^ 

426 132 264 

+ 3 Na2S04 + (NH4)2S04 +6 CO2. 

If it is a potash or soda alum, simply substitute K or 
Na for NH4 throughout the equation. The best authori- 
ties regard alum baking powders as the most objection- 
able. Ammonia alum is v/ithout doubt the worst form, 
since all of the ammonium compounds have an ex- 
tremely irritating effect on animal tissue. Sulphates of 
sodium and potassium are also objectionable. Alumin- 
ium hydroxide is soluble in the slightly acid gastric juice 
and has an astringent action on animal tissue, hindering 
digestion in a way similar to the alum itself. Many 
of the alum powders contain also monocalcium phos- 
phate ; the reaction is as follows : 

475 234 336 

2 NH4A1(S04)2 + CaH4(P04)2 + 4 NaHCOg 

245 136 132 

= Al2(P04)2 +CaS04 +(NH4)2S04 

284 176 72 

-f2Na2S04 +4CO2 4-4H2O. 

These are probably less injurious than the straight 



BAKING POWDERS IQI 

alum powders, although the residues are, ia general, 
open to the same objection. 

199. Inspection of Baking Powders. — Many of the 
states have enacted laws seeking to regulate the sale of 
alum baking powders. Some of these laws simply re- 
quire the packages to bear a label setting forth the fact 
that alum is one of the ingredients ; others require the 
baking powder packages to bear a label naming all the 
ingredients of the powder. 

200. Fillers. — All baking powders contain a filler of 
starch. This is necessary to keep the materials from 
acting before the powder is used. The amount of filler 
varies from 15 to 50 per cent ; the least is found in the 
tartrate powders and the most in the phosphate powders. 
The amount of gas which a powder gives off regulates 
its value ; it should give off at least ^ of its weight. 

201. Home-made Baking Powders. — Baking powders 
can be made at home for about one half what they usu- 
ally cost and they will give equal satisfaction. The fol- 
lowing will make a long-keeping powder : cream of tartar, 
8 ounces; baking soda, 4 ounces; corn starch, 3 ounces. 
For a quick- acting powder use but one ounce of starch. 
The materials should be thoroughly dry. Mix the soda 
and starch first by shaking well in a glass or tin 
can. Add the cream of tartar last and shake again. 
Thorough mixing is essential to good results. Cream 



192 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

of tartar is often adulterated, but it can be obtained 
pure from a reliable druggist. To insure baking pow- 
ders remaining perfectly dry, they should always be 
kept in glass or tin cans, never in paper. 



CHAPTER XIII 

VINEGAR, SPICES, AND CONDIMENTS 

202. Vinegar. — Vinegar is a dilute solution of acetic 
acid produced by fermentation, and contains, in addition 
to acetic acid, small amounts of other materials in solution, 
as mineral matter and malic acid, according to the ma- 
terial from which the vinegar was made. Unless other 
wise designated, vinegar in this country is generally 
considered to be made from apples. Other substances, 
however, are used, as vinegar can be manufactured from 
a variety of fermentable materials, as niolasses, glucose, 
malt, wine, and alcohoHc beverages in general. The 
chemical changes which take place in the production of 
vinegars are : (i) inversion of the sugar, (2) conversion 
of the invert sugars into alcohol, and (3) change of 
alcohol into acetic acid. All these chemical changes 
are the result of ferment action. The various invert 
ferments change the sugar into dextrose and glucose 
sugars ; then the alcoholic ferment produces alcohol and 
carbon dioxid from the invert sugars, and finally the 
acetic acid ferment completes the work by converting 
the alcohol into acetic acid. The chemical changes 
which take place in these different steps are ; 
193 



194 HUMAN FOODS AND THFJR NUTRITIVE VALUE 

sucrose dextrose levulose 

(i) Ci,H,,Oii -h H.p = QHi206 -h QHi^Oe; 

dextrose alcohol 

(2) QH^p, - 2 C2H5OH + 2 CO2 ; 

alcohol acid 

(3) C2H5OH + 20 = HC0H3O, + H.p. 




Fig. 52. — Acetic Acid Fp:rments, (After Konig.) 

The acetic acid organism, viycodcrma acti, can work 
only in the presence of oxygen. It is one of the aerobic 
ferments, and is present in what is known as the 
*' mother" of vinegar and is secreted by it. When vin- 
egar is made in quantity, the process is hastened by 



VINEGAR, SPICES, AND CONDIMENTS I95 

allowing the alcoholic solution to pass through a narrow 
tank filled with shavings containing some of the ferment 
material, and at the same time air is admitted so as to 
secure a good supply of oxygen. When vinegar is 
made by allowing cider or wine to stand in a warm 
place until the fermentation process is completed, a long 
time is required — the length of time depending upon 
the supply of air and other conditions affecting fermen- 
tation. 

In some countries malt vinegar is common. This is 
produced by allowing a wort made from malt and barley 
to undergo acetic acid fermentation, without first dis- 
tilling the alcohol as is done in the preparation of spirit 
vinegar. In various European countries wine vinegar 
is in general use and is made by acetification of the juice 
of grapes. Sometimes spirit vinegar is made from corn 
or barley malt. Alcoholic fermentation takes place, the 
alcohol is distilled so that a weak solution remains, 
which is acetified in the ordinary way. Such a vinegar 
can be produced very cheaply and is much inferior in 
flavor to genuine wine or cider vinegar. 

Vinegar, when properly made, should remain clear, 
and should not form a heavy deposit or produce any 
large amount of the fungous growth, commonly called 
the " mother " of vinegar. In order to prevent the vine- 
gar from becoming cloudy and forming deposits, it should 
be strained and stored in clean jugs and protected from 
the air. So long as air is excluded further acetic acid 
fermentation and production of "mother" of vinegar 



196 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

cannot take place. When the vinegar is properly made 
and the fermentation process has been completed, the 
acid already produced prevents all further development 
of acetic acid ferments. When vinegar becomes cloudy 
and produces deposits, it is an indication that the acetic 
fermentation has not been completed. 

The national standard for pure apple cider vinegar 
calls for not less than 4 grams acetic acid, 1.6 grams of 
apple solids, and 0.25 grams of apple ash per 100 cubic 
centimeters, along with other characteristics, as acidity, 
sugar, and phosphoric acid content. Many states have 
special laws regarding the sale of vinegar. 

203. Adulteration of Vinegar. — Vinegar is frequently 
adulterated by the addition of water, or by coloring 
spirit vinegar, thus causing it to resemble cider vinegar. 
Formerly vinegar was occasionally adulterated by the use 
of mineral acids, as hydrochloric or sulphuric, but since 
acetic acid can be produced so cheaply, this form of 
adulteration has almost entirely disappeared. Colored 
spirit vinegar contains merely a trace of solid matter 
and can be readily distinguished from cider vinegar by 
evaporating a small weighed quantity to dryness and 
determining the weight of the solids. Occasionally, how- 
ever, glucose and other materials are added so as to 
give some soHds to the spirit vinegar, but such a vin- 
egar contains only a trace of ash.^^ Attempts have also 
been made to carry the adulteration still further by 
addinsc lime and soda to give the colored spirit vin- 



VINEGAR, SPICES, AND CONDIMENTS 1 97 

egar the necessary amount of ash. Malt, white wine, 
glucose, and molasses vinegars when properly manufac- 
tured and unadulterated are not objectionable, but too 
frequently they are made to resemble and sell as cider 
vinegar. This is a fraud which affects the pocketbook 
rather than the health. For home use apple cider vin- 
egar is highly desirable. There is no food material 
or food adjunct, unless possibly ground coffee and spices, 
so extensively adulterated as vinegar. 

Vinegar has no food value whatever, and is valuable 
only for giving flavor and palatability to other foods, 
and to some extent for the preservation of foods. It is 
useful in the household in other ways, as it furnishes a 
dilute acid solution of aid in some cooking and baking 
operations for liberating gas from soda, and also when 
a dilute acid solution is required for various cleaning 
purposes. 

Vinegar should never be kept in tin pails, or any 
metallic vessel, because the acetic acid readily dissolves 
copper, tin, iron, and the ordinary metals, producing 
poisonous solutions. Earthenware jugs, porcelain dishes, 
glassware, or wooden casks are all serviceable for storing 
vinegar. 

204. Characteristics of Spices.""^ — Spices are aromatic 
vegetable substances characterized as a class by contain- 
ing some essential or volatile oil which gives taste and 
individuality to the material. They are used for the 
flavoring of food and are composed of mineral matter 



198 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

and the various nitrogenous and non-nitrogenous com- 
pounds found in all plant bodies. Since only a com- 
paratively small amount of a spice is used for flavoring 
purposes, no appreciable nutrients are added to the 
food. Some of the spices have characteristic medicinal 
properties. Occasionally they are used to such an ex- 
tent as to mask the natural flavors of foods, and to con- 
ceal poor cooking and preparation or poor quality. For 
the microscopic study of spices the student is referred to 
Winton, " Microscopy of Vegetable Foods," and Leach, 
" Food Inspection and Analysis." 

205. Pepper. — Black and white pepper are the fruit 
of the pepper plant {Piper nignun), a climbing perennial 
shrub which grows in the East and West Indies, the 
greatest production being in Sumatra. For the black 
pepper, the berry is picked before thoroughly ripe ; for 
the white pepper, it is allowed to mature. White pepper 
has the black pericarp or hull removed. Pepper owes 
its properties to an alkaloid, piperine, and to a volatile 
oil. In the black pepper berries there is present ash to 
the extent of about 4.5 per cent, it ought not to be 
above 6.5 per cent; ether extract, including piperine and 
resin, not less than 6.5 per cent; crude fiber not more 
than 16 per cent ; also some starch and nitrogenous 
material. The white pepper contains less ash and cel- 
lulose than the black pepper. Ground pepper is fre- 
quently grossly adulterated ; common adulterants being : 
cracker crumbs, roasted nut shells and fruit stones. 



VINEGAR, SPICES, AND CONDIMENTS I99 

charcoal, corn meal, pepper hulls, mustard hulls, and 
buckwheat middhngs. The pepper berries wrinkle in 
drying, and this makes it difficult to remove the sand 
which may have adhered to them. An excessive amount 
of sand in the ash should be classed as adulteration. 
Adulterants in pepper are detected mainly by the use 
of the microscope. The United States standard for pep- 
per is : not more than 7 per cent total ash, 15 per cent 
fiber, and not less than 25 percent starch and 6 per cent 
non-volatile ether extract."^ 

206. Cayenne. — Cayenne or red pepper is the fruit 
pod of a plant, capsiacm, of which there are several 
varieties, — the small-fruited kind, used to make cayenne 
or red pepper; and the tabasco sort, forming the basis of 
tabasco sauce. It is grown mainly in the tropics, and 
was used there as a condiment before the landing 
of Columbus, who took specimens back to Europe. 
Cayenne pepper contains 25 per cent of oil, about 7 per 
cent of ash, and a liberal amount of starch. The adul- 
terants are usually of a starchy nature, as rice or corn 
meal, and the product is often colored with some red 
dye. 

207. Mustard. — Mustard is the seed of the mustard 
plant, and is most often found in commerce in the 
ground form. The black or brown mustard has a very 
small seed and the most aroma. White mustard is 
much larger and is frequently used unground. For the 
ground mustard, only the interior of the seed is used, the 



200 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

husk being removed in the bolting. Mustard contains 
a large amount of oil, part of which is usually expressed 
before grinding, and this is the form in which spice 
grinders buy it. In mustard flour there is : ash from 
4 to 6 per cent, volatile oil from 0.5 to 2 per cent, fixed oil 
from 15 to 25 per cent, crude fiber from 2 to 5 per cent, 
albuminoids from 35 to 45 per cent, and a little starch. 
The principal adulterants are wheat, corn, and rice flour. 
When these are used, the product is frequently colored 
with turmeric, a harmless vegetable coloring material. 

208. Ginger. — Ginger is the rhizome or root of a 
reed-like plant {Ziiigiber officinale), native in tropical 
Asia, chiefly India. It is cultivated in nearly all tropical 
countries. When unground it usually occurs in two 
forms : dried with the epidermis, or with the epidermis 
removed, when it is called scraped ginger. Very fre- 
quently a coating of chalk is given, as a protection 
against the drug store beetle. Jamaica ginger is the 
best and most expensive. Cochin, scraped, African, and 
Calcutta ginger range in price in the order given. Gin- 
ger contains from 3.6 to 7.5 per cent of ash, from 1.5 to 
3 per cent of volatile oil, and from 3 to 5.5 per cent of 
fixed oil. There is a large amount of starch. The chief 
adulterants are rice, wheat, and potato starch, mustard 
hulls, exhausted ginger from ginger-ale and extract 
factories, sawdust and ground peanutshells, and tur- 
meric is frequently used for coloring the product. The 
United States standard for ginger is not more than 42 



VINEGAR, SPICES, AND CONDIMENTS 20I 

per cent starch, 8 per cent fiber, and 6 per cent total 
ash.'^ 

209. Cinnamon and Cassia. — The bark of several 
species of plants growing in tropical countries fur- 
nishes these spices. True cinnamon is a native of 
Ceylon, while the cassias are from Bengal and China. 
In this country there is more cassia used than cinna- 
mon — cinnamon being rarely found except in drug 
stores. Cassia bark is much thicker than cinnamon 
bark. The ground spice contains about 1.5 per cent 
volatile oil and the same amount of fixed oil, 4 per 
cent of ash, and some fiber, nitrogenous matter, and 
starch. Cereals, cedar sawdust, ground nutshells, 
oil meal, and cracker crumbs are the chief adulterants. 

210. Cloves. — Cloves are the flower buds of an 
evergreen tree that grows in the tropics. These are 
picked by hand and dried in the sun. In the order 
of value, Penang, Sumatra, Amboyna, and Zanzibar 
furnish the chief varieties. Cloves rarely contain 
more than 8 per cent ash, or less than 10 per cent 
volatile oil and 4 per cent fixed oil, and 16 to 20 per 
cent of tannin-yielding bodies. No starch is present. 
The chief adulterants of ground cloves are spent 
cloves, allspice, and ground nutshells. Clove stems 
are also sometimes used and may be detected by a 
microscopical examination, since they contain many 
thick-walled cells and much fibrous tissue. 



202 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

211. Allspice. — Allspice, or pimento, is the fruit of 
an evergreen tree common in the West Indies. It 
is a small, dry, globular berry, two-celled, each cell 
having a single seed. Allspice contains about 2.5 per 
cent volatile oil, 4 per cent fixed oil, and 4.5 per cent 
ash. Because of its cheapness, it is not generally 
adulterated, cereal starches being the most common 
adulterants. 

212. Nutmeg. — Nutmeg is the interior kernel of 
the fruit of a tree growing in the East Indies. The 
fruit resembles a small pear. A fleshy mantle of 
crimson color, which is mace, envelopes the seed. 
Nutmeg contains about 2.2 per cent ash, 2.5 to 5 per 
cent volatile oil, and 25 to 35 per cent fixed oil. 
Mace has practically the same composition. Exten- 
sive adulteration is seldom practiced. The white 
coating on the surface of the nutmeg is lime, used to 
prevent sprouting of the germ. 



CHAPTER XIV 
TEA, COFFEE, CHOCOLATE, AND COCOA 



213. Tea is the prepared leaf of an evergreen shrub 
or small tree cultivated chiefly in China and Japan. 
There are two varieties of plants. 
The Assamese, which requires 
a very moist, hot climate, yields 
in India and Ceylon about 400 
pounds per acre, and may pro- 
duce as high as looo pounds. 
From this plant a number of 
flushes or pickings are secured 
in a year. The Chinese plant 
grows in cooler climates and has 
a smaller, tougher, and darker 
leaf, which is more deUcate than 
that of the Assamese and is 
usually made into green tea. 
The Chinese tea plant yields 
only four or five flushes a year. 
About 40 per cent of the tea 
used in this country comes from 
Japan and 50 per cent from China. The tea industry 
of India and Ceylon has developed rapidly in late years, 
and is now second only to that of China. Tea has been 
raised upon a small scale in the United States. The 
quality or grade of the tea depends upon the leaves 
used and the method of curing. 




Fig. 53. — Tea Leak 
(After WiNTON.) 



204 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

214. Composition of Tea. — Black and green teas 
are produced from the same species of plant, but owe 
their difference in color as well as flavor and odor to 
methods of preparation. The same plant may yield 
several grades of both green and black tea. To pro- 
duce black tea, the leaves are bruised to Uberate the 
juices, allowed to ferment a short time, which develops 
the color, and then dried. '^ For green tea the fresh 
leaves are roasted or steamed, then rolled and dried 
as quickly as possible to prevent fermentation. The 
smaller leaves and the first picking produce the finest 
quality of tea. The characteristic flavor and odor of 
tea are imparted by a volatile oil, although the odor is 
sometimes altered by the tea being brought in contact 
with orange flowers, jessamine, or the fragrant olive. 
There are also present in tea an alkaloid, theine, which 
gives the peculiar physiological properties, and tannin, 
upon which depends largely the strength of the tea 
infusion. The composition of tea is as follows : 



Tannin, per cent 

Theine, per cent 

Ash, per cent 

Fiber, per cent 

Protein, per cent (all insoluble) 




Green Tea 



10.64 
3.20 
4.92 

10.06 

37-43 



Black Tea 



4.89 
3-30 

493 
10.07 
38.90 



It will be noticed that green tea contains twice as 
much tannin as black tea ; during the fermentation 



TEA, COFFEE, CHOCOLATE, AND COCOA 205 

which the black tea undergoes, some of the tannin is 
decomposed. There is a large amount of protein in 
tea, but it is of no food value, because of its insolu- 
bility. About half of the ash is soluble. The tannin 
is readily soluble, and for this reason green tea es- 
pecially should be infused for a very short time and 
never boiled. Tannin in foods in large amounts 
may interfere with the normal digestion of the protein 
compounds, because it coagulates the albumin and 
peptones after they have become soluble, and thus 
makes additional work for the digestive organs. 

215. Judging Teas. — Teas are judged according to : 
(i)the tea as it appears prepared for market, (2) the 
infusion, and (3) the out-turn after infusion. The 
color should be uniform ; if a black tea, it should be 
grayish black, not a dead black. The leaves should 
be uniform in size or grade. The quality and grade 
are dependent upon flavor, and, with the strength 
of the infusion, are determined by tasting. This work 
is rapidly done by the trained tea taster. The out- 
turn should be of one color ; no bright green leaves 
should be present ; evenness of make is judged by 
the out-turn. The flavor of a tea is largely a matter 
of personal judgment, but from a physiological point 
of view black teas are given the preference. 

216. Adulteration of Tea. — A few years ago tea 
was quite extensively adulterated, but the strict regu- 
lation of the government regarding imported tea has 



2o6 HUMAN FOODS AND THEIR NUTRITIVP: VALUE 

greatly lessened adulteration. The most common form 
was the use of spent leaves, i.e. leaves which had 
been infused. Leaves of the willow and other plants 
which resemble tea were also used, as well as large 
quantities of tea stems. Facing or coloring is also 
an adulteration, since it is done to give poor or 
damaged tea a brighter appearance. ** Facing con- 
sists in treating leaves damaged in manufacture or 
which from age are inferior, with a mixture contain- 
ing Prussian blue, turmeric, indigo, or plumbago to 
impart color or gloss, and with a fraudulent intent. 
There is no evidence that the facing agents are 
deleterious to health in the small quantities used, but as 
they are used for purposes of deception, they should be 
discouraged." '^ Facing and the addition of stems are 
the chief adulterations practiced at present. 

217. Food Value and Physiological Properties of Tea. 

— Tea infusion does not contain sufficient nutrients 
to entitle it to be classed as a food. It is with some 
persons a stimulant. The caffein or theine in tea is 
an alkaloid that has characteristic physiological proper- 
ties. In doses of from three to five grains, accord- 
ing to the United States Dispensatory, " it produces 
pecuUar wakefulness." Larger doses produce intense 
physical restlessness, mental anxiety, and obstinate 
sleeplessness. *' It has no effect upon the motor 
nerves, but is believed to have a visible effect upon 
the sensatory nerves." (United States Dispensatory.) 



TEA, COFFEE, CHOCOLATE, AND COCOA 207 

Experiments with animals show that it causes eleva- 
tion of the arterial pressure. It is used as a cardiac 
stimulant. The quantity of theine consumed in a cup 
of tea is about | of a grain, or J of a medicinal dose. 



1 




« 


/, 




m 


z 


^m o^o 







® ® ^ ^ €1 


m 


3. 




• 






• 



Fig. 54. ^Coffee Berries. 
I, Mocha; 2, Java; 3, Rio. 

218. Composition of Coffee. — The coffee tree is an 
evergreen cultivated in the tropics. It grows to a height 
of 30 feet, but when cultivated is kept pruned to from 
6 to 10 feet. The fruit, which resembles a small cherry, 
with two seeds or coffee grains embedded in the pulp, 
is dried and the seeds removed, cleaned, and graded. 
Coffee has an entirely different composition from tea ; 



208 HUMAN FOODS AND THEIR NUTRITIVE VALUE 



it is characterized by a high per cent of fat and soluble 
carbohydrates, and also contains an essential oil and 
caffein, an alkaloid identical with theine. Tannic acid, 
not as free acid, is combined with caffein as a tannate. 



Raw Coffe;^e 



Roasted Coffee 



Water . 
Ash . . 
Fat . . 
Sugar, etc. 
Protein . 
Caffein . 



Per Cent 
11.23 

3-92 
12.27 

0.66 
12.07 

1. 21 



Per Cent 
1. 15 

4 75 

14.48 

8.55 

1398 
1.24 



The high per cent of sugar and other soluble carbohy- 
drates in roasted coffee is caused by the action of heat 
upon the non-nitrogenous compounds. Coffee cannot 
be considered a food, because only a comparatively small 
amount of the nutrients are soluble and available. It is 
a mildly stimulating beverage. With some individuals 
it appears to promote the digestive process, while with 
others its effect is not beneficial. Coffee is more exten- 
sively used in this country than tea, and is subject to 
greater adulteration. It is adulterated by facing and 
glazing ; i.e. coloring the berries to resemble different 
grades and coating them with caramel and dextrine. 
Spent coffee grains and coffee that has been extracted 
without grinding are also used as adulterants. Imitation 
berries made of rye, corn, or wheat paste, molded, 
colored with caramel, and baked have been found mixed 



TEA, COFFEE, CHOCOLATE, AND COCOA 209 

with genuine coffee berries. Roasted cereals and chic- 
ory are used extensively to adulterate ground coffee. 
Chicory is prepared from the root of the chicory plant, 
which belongs to the same family as the dandeUon. It 
is claimed by some that a small amount of chicory im- 
proves the flavor of coffee. However, when chicory is 
added to coffee, it should be so stated on the label and 
the amount used given. The dextrine and sugar used 
in glazing are browned or caramelized during roasting 
and impart a darker color to the infusion, making it ap- 
pear better than it really is. The glazing also makes 
the coffee retain moisture which would otherwise be 
driven off during roasting. Coffee contains such a large 
per cent of oil that the berries generally float when thrown 
on water, while the imitation berries sink. Chicory also 
sinks rapidly and colors the water brown, while the cof- 
fee remains floating for some time. 

There are three kinds of coffee in general use : Java, 
Mocha, and Rio or Brazil. The Brazil coffee has 
the largest berry and is usually styled by dealers as 
"low" or *'low middlings." The Java coffee berries are 
smaller and paler in color, the better grades being 
brown. Mocha usually commands the highest price in 
commerce. The seeds are small and dark yellow 
before roasting. 

219. Cereal Coffee Substitutes. 

'' A few of these preparations contain a little true coffee, but for 
the most part they appear to be made of parched grains of barley, 
wheat, etc., or of grain mixed with pea hulls, ground corncobs, or 
p 



2IO HUMAN FOODS AND THEIR NUTRITIVE VALUE 

wheat middlings. It is said that barley or wheat parched, with a 
little molasses, in an ordinary oven, makes something indistinguish- 
able in flavor from some of the cereal coffees on the market. If no 
coffee is used in the cereal preparations, the claim that they are not 
stimulating is probably true. As for the nutritive value, parching 
the cereals undoubtedly renders some of the carbohydrates soluble, 
and a part of this soluble matter passes into the decoction, but the 
nutritive value of the infusion is hardly worth considering in the 
dietary." ^^ 

220. Cocoa and Chocolate Preparations. — Cocoa and 
chocolate are manufactured from the *' cocoa bean," 
the seed of a tree native to tropical America. The 
beans are inclosed in a lemon-yellow, fleshy pod. They 
are removed from the pulp, allowed to undergo fermen- 
tation, and dried by exposure to the air and light, which 
hardens them and gives them a red color. This method 
produces what is known as the "fermented cocoa." 
For the *' unfermented cocoa," the beans are dried with- 
out undergoing fermentation. Fermentation removes 
much of the acidity and bitterness characteristic to the 
unfermented bean, and when properly regulated develops 
flavor. The original bean contains about 50 per cent 
fat, part of which is removed in preparing the cocoa. 
This fat is sold as cocoa butter. In the preparation of 
some brands of cocoa, alkalies, such as soda and potash, 
are used to form a combination with the fat to prevent 
its separating in oily globules. This treatment improves 
the appearance of the cocoa, but experiments show the 
albumin to be somewhat less digestible and the soap- 
like product resulting not as a valuable food as the 



TEA, COFFEE, CHOCOLATE, AND COCOA • 211 

fat. Such preparations have a high per cent of ash. 
There is no objection from a nutritive point of view 
to a cocoa in which the fat separates in oily globules. 

221. Composition of Cocoa. — The cocoa bean, when 
dried or roasted and freed from its husk and ground, is 
sold as cracked cocoa, or cocoa nibs. From cocoa nibs 
the various cocoa and chocolate preparations are made. 
Cocoas vary in composition according to the extent to 
which the fat is removed during the process of manu- 
facture and the nature and extent to which other ingre- 
dients are added. An average cocoa contains about 20 
per cent of proteids, and 30 per cent fat, also starch, 
sugar, gums, fiber, and ash, as well as theobromine, a 
material very similar to theine and caffein in tea and 
coffee, but not such an active stimulant. Cocoa is not 
easily soluble, but it may be ground so fine that a long 
time is required for its sedimentation; or sugar or other 
soluble material may be added during the process of 
manufacture to increase the specific gravity of the liq- 
uid to such an extent that the same object is attained 
without such fine grinding. The first method is to be 
preferred. Cocoa and its preparations are richer in 
nutritive substances than tea and coffee and have this 
added advantage that both the soluble and insoluble 
portions become a part of the beverage. Owing to the 
small amount used for a cup of cocoa, independent of 
the milk it does not add much in the way of nutrients 
to the ration. 



212 HUMAN FOODS AND TKEIR NUTRITIVE VALUE 

222. Chocolate. — Plain chocolate is prepared from 
cocoa nibs without '* removal of the fat or other constit- 
uents except the germ." It differs in chemical com- 
position from cocoa by containing more fat and less 
protein ; it has nearly the same chemical composition as 
the cocoa nibs. It is officially defined as containing 
" not more than 3 per cent of ash insoluble in water, 
3^^ per cent of crude fiber and 9 per cent of starch, and 
less than 45 per cent cocoa fat." '^ 

By the addition of sugar, sweet chocolates are made. 
They vary widely in composition according to the fla- 
vors and amounts of sugar added during their prepara- 
tion. The average composition of cocoa nibs, standard 
cocoa, and plain chocolate is as follows: 









Cocoa 
Nibs 


Composition of 
Standard Cocoa 


Composition of 
Plain Chocolate 


Water . . . 

Ash ... . 
Theobromine . 
Caflfein . . . 
Crude Protein . 
Crude fiber . . 
Fat 






Per Cent 
3.00 

3-5° 

1. 00 
0.50 

12.00 
2.50 

50.00 

27.50 


Per Cent 



4 20 

5.02 
32.52 


Per Cent 
3-09 
3.08 

2.63 
49.81 


Starch and other non 
nitrogenous matter 





223. Adulteration of Chocolate and Cocoa. — The vari- 
ous chocolate and cocoa preparations offer an enticing 
field for sophistication; they are not, however, so exten- 



TEA, COFFEE, CHOCOLATE AND COCOA 



213 



sively adulterated as before the enforcement of national 
and state pure food laws. The most common adulter- 
ants are starch, cocoa shells, and occasionally iron dioxid 
and other pigments to give color, also foreign fats 
to replace the fat removed and to give the required 
plasticity for molding. 

224. Comparative Composition of Beverages. — Tea 

and coffee as beverages contain but little in the way of 

nutrients other than the cream and sugar used in them. 

The solid matter in tea and coffee infusions amounts to 

less than 1.2 per cent. When cocoa is made with milk, 

it is a beverage of high nutritive value due mainly to 

the milk. 

Composition of Beverages ^^ 



Kind of Beverage 


Water 


Protein 


Fat 


Carbo- 
hydrates 


Fuel 
Value 
PER Lb. 




Per Cent 


Per Cent 


Per Cent 


Per Cent 


Calories 


Commercial cereal coffee (0.5 












ounce to i pint water) . . 


98.2 


0.2 


— 


1.4 


30 


Parched corn coffee (1.6 












ounces to i pint water) . 


99-5 


0.2 


— 


0.5 


13 


Oatmeal water (i ounce to i 












pint water) 


99-7 


03 


— 


0-3 


II 


Coffee (i ounce to i pint 












water) 


98.9 


0.2 


— 


0.7 


16 


Tea (0.5 ounce to i pint 












water) 


99-5 


0.2 


— 


0.6 


15 


Cocoa (0.5 ounce to i pint 












milk) 


84.5 


3.B 


4-7 


6.0 


.36s 


Cocoa (0.5 ounce to 1 pint 












water) 


97.1 


06 


0.9 


I.I 


6S 


Skimmed milk 


90.5 


3-4 


0-3 


5-1 


170 



CHAPTER XV 
THE DIGESTIBILITY OF FOODS 

225. Digestibility, How Determined. — The term 
** digestibility," as applied to foods, is used in two 
ways: (i) meaning the thoroughness of the process, 
or the completeness with which the nutrients of the 
food are absorbed and used by the body, and (2) mean- 
ing the ease or comfort with which digestion is accom- 
plished. Cheese is popularly termed indigestible, and 
rice digestible, when in reality the nutrients of cheese 
are more completely although more slowly digested 
than those of rice. In this work, unless otherwise 
stated, digestibiUty is applied to the completeness of 
the digestion process. 

The digestibility of a food is ascertained by means of 
digestion experiments, in which all of the food consumed 
for a certain period, usually two to four days, is weighed 
and analyzed, and from the weight and composition is 
determined the amount, in pounds or grams, of each nu- 
trient consumed.'^ In like manner the nutrients in the 
indigestible portion, or feces, are determined from the 
weight and composition of the feces. The indigestible 

214 



THE DIGESTIBILITY OF FOODS 



215 



nutrients in the feces are deducted from the total nu- 
trients of the food, the difference being the amount 
digested, or oxidized in the body. When the food is di- 
gested, the various nutrients undergo complete or partial 
oxidation, with the formation of carbon dioxid gas, water, 
urea (CH^NgO), and other compounds. The feces con- 
sist mainly of the compounds which have escaped diges- 
tion. The various groups of compounds of foods do not 
all have the same digestibility ; for example, the starch 
of potatoes is 92 per cent digestible, while the protein 
is only 72 per cent. The percentage amount of a 
nutrient that is digested is called the digestion coeffi- 
cient. 

In the following way the digestibiUty of a two-days 
ration of bread and milk was determined : 773.5 grams 
of bread and 2000 grams of milk were consumed by the 
subject. The dried feces weighed 38.2 grams. The foods 
and feces when analyzed were found to have the follow- 
ing composition : ^^ 



Composition 



Water .... 
Crude protein 
Ether extract 
Ash .... 
Carbohydrates . 
Calories per gram 



Bread 



44.13 

775 

0.90 

0.32 

46.90 

2.450 



Milk 



86.52 
•15 
•63 

.70 
.00 

•79 



Feces' 



25.88 
18.23 
26.35 
29.54 
5.083 



* Results on dry-matter basis. 



2I( 



HUMAN FOODS AND THEIR NUTRITIVE VALUE 



Statement of Results of a Digestion Experiment 



Food Consumed 


a < 


Is 






X 

< 


Heat of 

Combus- 
tion 




Grams 


Grams 


Grams 


Grams 


Grams 


Calories 


Bread 


773-5 


60.0 


6.9 


362.8 


2.5 


1895 


Milk 


20OO.O 
38.2 


63.0 


92.6 


1 00.0 


14.0 


1585 


Total .... 


123.0 


99-5 


462.8 


16.5 


3480 


Feces 




99 


7.0 


II.3 


lO.I 


194 


Total amount digested 


II3.I 


92.5 


451.5 


6.4 


3286 


Per cent digested or 














coefficients of diges- 














tibility 




92.0 


93-0 


97-5 


38.8 


94.4 


Available energy . . 




— 


~ 




— 


90.0 



In this experiment 92 per cent of the crude protein, 
93 per cent of the ether extract, and 97.5 per cent of 
the carbohydrates of the bread and milk ration were 
digested and absorbed by the body. In calculating the 
available energy, correction is made for the unoxidized 
residue, as urea and allied forms. It is estimated that 
for each gram of protein in the ration there was an in- 
digestible residue yielding 1.25 calories. 



226. Available Nutrients. — A food may contain a 
comparatively large amount of a compound, and yet, 
on account of its low digestibility, fail to supply much 
of it to the body in an available form. Hence it is 



THE DIGESTIBILITY OF FOODS 217 

that the vahie of a food is dependent not alone on its 
composition, but also on its digestibility. The digestible 
or available nutrients of a food are determined by mul- 
tiplying the per cent of each nutrient which the food 
contains by its digestion coefficient. For example, a 
sample of wheat flour contains 12 per cent protein, 
88 per cent of which is digestible, making 10.56 per 
cent of available or digestible protein (12 x 0.88 — 10.56). 
Graham flour made from similar wheat contains 13 per 
cent total protein, and only 75 per cent of the protein is 
digestible, making 9.75 per cent available (13 x 0.75 = 
9.75). Thus one food may contain a larger total but a 
smaller available amount of a nutrient than another. 

227. Available Energy. — The available energy of a 
food or a ration is expressed in calories. A ration for a 
laborer at active out-of-door work should yield about 3200 
calories. The calory is the unit of heat, and represents 
the heat required to raise the temperature of a kilo- 
gram of water 1° C, or four pounds of water 1° F. The 
caloric value of foods is determined by the calorimeter, 
an apparatus which measures heat with great accuracy. 
A pound of starch, or alUed carbohydrates, yields i860 
calories, and a pound of fat 4225 (see Section 13). While 
a gram of protein completely burned produces y.8 
calories, digested it yields only about 4.2 calories, be- 
cause, as explained in the preceding section, not all of 
the carbon and oxygen are oxidized.^^ The caloric 
value or available energy of a ration can be calculated 




Fig. 55.— Calorimeter. 
218 



THE DIGESTIBILITY OF FOODS 219 

from the digestible nutrients by multiplying the pounds 
of digestible protein and carbohydrates by i860, the 
digestible fat by 4225, and adding the results. For 
determination of the available energy of foods under 
different experimental conditions, and where great ac- 
curacy is desired, a specially constructed respiration 
calorimeter has been devised, which is built upon the 
same principle as an ordinary calorimeter, except it is 
large enough to admit a person, and is provided with 
appliances for measuring and analyzing the intake and 
outlet of air.*"* The heat produced by the combustion 
of the food in the body warms the water surrounding 
the calorimeter chamber, and this increase in tempera- 
ture is determined by thermometers reading to 0.005 of 
a degree or less. 

228. Normal Digestion and Health. — While the pro- 
cess of digestion has been extensively studied, it is not 
perfectly understood. Between the initial compounds 
of foods and their final oxidation products a large num- 
ber of intermediate substances are formed, and when 
digestion fails to take place in a normal way, toxic or 
poisonous compounds are produced and various diseases 
result. It is probable that more diseases are due to 
imperfect or malnutrition than to any other cause. 
There is a very close relationship between health and 
normal digestion of the food. 

The cells in the different parts of the digestive 
tract secrete fluids containing substances known as 



2 20 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

soluble ferments, or enzymes, which act upon the vari- 
ous compounds of foods, changing them chemically and 
physically so that they can be absorbed and utilized by 
the body. (See Section 31.) Some of the more impor- 
tant ferments are: ptyolin of the saliva, pepsin of the 
stomach, and pancreatin and diastase of the intestines. 
In order that these ferments may carry on their work in 
a normal way, the acidity and alkahnity of the different 
parts of the digestive tract must be maintained. The 
gastric juice contains from o.i to 0.25 per cent of hydro- 
chloric acid, imparting mildly antiseptic properties ; and 
while the peptic ferment works in a slightly acid solu- 
tion, the tryptic ferment requires an alkaline solution. 
To secrete the necessary amount and quality of diges- 
tive' fluids, the organs must be in a healthy condition. 
Many erroneous ideas regarding the digestion of foods 
are based upon misinterpretation of facts by persons 
suffering from impaired digestion, and attempts are fre- 
quently made to apply to normal digestion generaliza- 
tions applicable only to diseased conditions. 

229. Digestibility of Animal Foods. — The proteids 

and fats in animal foods, as meats, are more completely 
digested than the same class of nutrients in vegetables. 
In general, about 95 per cent of the proteids of meats 
is digestible, while those in vegetables are often less 
than 85 percent digestible. The amount of indigestible 
residue from animal foods is small; while from vege- 
tables it is large, for the cellulose prevents complete 



THE DIGESTIBILITY OF FOODS 221 

absorption of the nutrients and, as a result, there is 
much indigestible residue. Animal foods are concen- 
trated, in that they furnish large amounts of nutrients 
in digestible forms. There is less difference in the 
completeness with which various meats are digested 
than in their ease of digestion ; the proteins all have 
about the same digestion coefficients, but vary with 
individuals as to ease of digestion and time required. 
It is generally considered that the digestible proteins, 
whether of animal or vegetable origin, are equally valu- 
able for food purposes. This is an assumption, how- 
ever, that has not been well established by experimental 
evidence. In a mixed ration, the proteins from different 
sources appear to have the same nutritive value, but as 
each is composed of different radicals and separated 
into dissimilar elementary compounds during the pro- 
cess of digestion, they would not necessarily all have 
the same food value. 

There is but little difference between the fats and 
proteins of meats as to completeness of digestion, — the 
slight difference being in favor of the proteins. Some 
physiologists claim that the fat, which in some meats 
surrounds the bundles of fiber (protein), forming a 
protecting coat, prevents the complete solvent action 
of the digestive fluid. Very fat meats are not as 
completely digested as those moderately fat. It is 
also claimed that the digestibility of the meat is influ- 
enced by the mechanical character, as toughness of the 
fiber. 



222 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

230. Digestibility of Vegetable Foods. — Vegetable 
foods vary in digestibility with their mechanical con- 
dition and the amount of cellulose or fiber. In some 
the nutrients are so embedded in cellular tissue as to be 
protected from the solvent action of the digestive fluids, 
and in such cases the digestibility and availability are 
low. The starches and sugars are more completely 
digested than any other of the nutrients of vegetables ; 
in some instances they are from 95 to 98 per cent di- 
gestible. Some cellular tissue, but not an excess, is 
desirable in a ration, as it exerts a favorable mechanical 
action upon the organs of digestion, encourages peri- 
stalsis, and is an absorbent and dilutant of the waste 
products formed during digestion. For example, in the 
feeding of swine, it has been found that corn and cob 
meal often gives better results than corn fed alone. 
The cob contains but Httle in the way of nutrients, but 
it exerts a favorable mechanical action upon digestion. 
Occasionally too many bulky foods are combined, con- 
taining scant amounts of nutrients, so that the body 
receives insufficient protein. This is liable to be the 
case in the dietary of the strict vegetarian. Many of 
the vegetables possess special dietetic value, due to the 
organic acids and essential oils, as cited in the chapter 
on fruits and vegetables. The value of such foods can- 
not always be determined from their content of digest- 
ible protein, fat, and carbohydrates. This is particularly 
evident when they are omitted from the ration, as in 
the case of a restricted diet consisting mainly of animal 



THE DIGESTIBILITY OF FOODS 223 

foods. Many vegetables have low nutritive value on 
account of their bulky nature and the large amount of 
water and cellulose which they contain, which tends to 
decrease digestibihty and lower the amount of available 
nutrients. Because of their bulk and fermentable na- 
ture, resulting in the formation of gases, a diet of coarse 
vegetables has a tendency to cause distention and en- 
largement of the intestinal organs. The carbohydrates, 
which are the chief constituents of vegetables, are 
digested mainly in the intestines, and require special 
mechanical preparation in the stomach, hence the nutri- 
ents of vegetables are not, as a rule, as easily digested 
as those of animal foods. 

231. Factors influencing Digestion. — There are a 
number of factors which influence completeness as well 
as ease of digestion, as: (i) combination of foods; 
(2) amount of food ; (3) method of preparation ; (4) me- 
chanical condition of the food ; (5)palatability; (6) phys- 
iological properties; (7) individuality of the consumer; 
and (8) psychological influences. 

232. Combination of Foods. — In a mixed ration the 
nutrients are generally more completely digested than 
when only one food is used. For example, milk is 
practically all digested when it forms a part of a ration, 
and it also promotes digestibility of the foods with which 
it is combined, but when used alone it is less digestible.^" 
Bread alone and milk alone are not as completely 
digested as bread and milk combined. The same in a 



224 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

general way has been observed in the feeding of farm 
animals, — better results are secured from combining 
two or more foods than from the use of one alone. The 
extent to which one food influences the digestibility of 
another has not been extensively studied. 

In a mixed ration, consisting of several articles of 
food of different mechanical structure, the work of 
digestion is more evenly distributed among the various 
organs. A food often requires special preparation on 
the part of the stomach before it can be digested in the 
intestines, and if this food is consumed in small amounts 
and combined with others of different structure, the 
work of gastric digestion is lessened so that the foods 
are properly prepared and normal digestion takes place. 
The effect which one food exerts upon the digestibility 
of another is largely mechanical. 

233. Amount of Food. — Completeness as well as 
ease of digestion is influenced by the amount of food 
consumed.' In general, excessive amounts are not as 
completely digested as moderate amounts. In digestion 
experiments with oatmeal and milk, it was found that 
when these foods were consumed in large quantities the 
fat and protein were not as completely absorbed by the 
body as when less was used, the protein being 7 per 
cent and the fat 6 per cent more digestible in the 
medium ration. Experiments with animals show that 
economical results are not secured from an excess of 
food.^ Some individuals consume too much food, and 



THE DIGESTIBILITY OF FOODS 22$ 

with them a restricted diet would be beneficial, while 
others err in not consuming enough to meet the re- 
quirements of the body. Quite frequently it is those 
who need more food who practice dieting. When there 
is trouble with digestion, it is not always the amount or 
kind of food which is at fault, but other habits may 
be such as to affect digestion. The active out-of-door 
laborer can with impunity consume more food, -because 
there is greater demand for nutrients, and the food is 
more completely oxidized in the body and without the 
formation of poisonous waste products. The amount of 
food consumed should be sufficient to meet all the 
demands of the body and maintain a normal weight. 

234. Method of Preparation of Food. — The extent to 
which methods of cooking and preparation influence 
completeness of digestion has not been extensively in- 
vestigated. As is well known, they have great influence 
upon ease and comfort of digestion. During cooking, 
as discussed in Chapter II, extensive physical and 
chemical changes occur, and these in turn affect digesti- 
bility. When the cooking has not been sufficient to 
mechanically disintegrate vegetable tissue, the digestive 
fluids fail to act favorably upon the food. Cooking is 
also beneficial because it renders the food sterile and 
destroys all objectionable microorganisms which, if they 
remain in food, readily undergo incubation in the digest- 
ive tract, interfering with normal digestion. Prolonged 
heat causes some foods to become less digestible, as milk, 
Q 



226 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

which digestion experiments show to be more completely 
digested when fresh than when sterilized. Pasteurized 
milk, which is not subjected to so high a temperature as 
sterilized milk, is more completely digested. See Chap- 
ter VII for discussion of sterilizing and pasteurizing 
milk.^^ The benefits derived from the destruction of 
the objectionable bacteria in foods are, however, greater 
than the losses attendant on lessened digestibility due 
to the action of heat. The method of preparation of a 
food affects its digestibility mainly through change in 
mechanical structure, and modification of the forms in 
which the nutrients are present.^ 

235. Mechanical Condition of Foods. — The mechanical 
condition of foods as to density and structure of the 
particles and the extent to which they are disintegrated 
in their preparation for the table influences digestibility 
to a great extent. The mechanics of digestion is a 
subject that has not been extensively investigated, and it 
is one of great importance, as biological and chemical 
changes cannot take place if the food is not in proper 
mechanical condition. In general, the finer the food 
particles, the more completely the nutrients are acted 
upon by the digestive fluids and absorbed by the body. 
Nevertheless, the diet should not consist entirely of finely 
granulated foods. Some foods are valuable mainly 
because of the favorable action they exert mechanically 
upon digestion, rather than for the nutrients they con- 
tain.^2 Coarsely granulated breakfast foods, whole 



THE DIGESTIBILITY OF FOODS 227 

wheat flour, and many vegetables contain sufficient 
cellular tissue to give special value from a mechanical 
rather than a chemical point of view. The extent to 
which coarsely and finely granulated foods should enter 
into the ration is a question largely for the individual to 
determine. Experiments with pigs show that if large 
amounts of coarse, granular foods are consumed, the 
tendency is for the digestive tract to become inflamed 
and less able to exercise its normal functions. Coarsely 
granulated foods have a tendency to pass through the 
digestive tract in less time than those that are finely 
granulated, due largely to increased peristaltic action, 
and the result is the food is not retained a sufficient 
length of time to allow normal absorption to take place. 
In the feeding of farm animals, it has been found that 
the mechanical condition of the food has a great influ- 
ence upon its economic use. Rations that are either 
too bulky or too concentrated fail to give the best results. 
In the human ration, the mechanical condition of the 
food is equally as important as its chemical composi- 
tion. 

236. Mastication is an important part of digestion, 
and when foods are not thoroughly masticated, addi- 
tional work is required of the stomach, which is usually 
an overworked organ because of doing the work of the 
mouth as well. Although much of the mechanical 
preparation and mixing of foods is of necessity done in 
the stomach, some of it may advantageously be done in 



228 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

the mouth. The stomach should not be required to 
perform the function of the gizzard of a fowl. 

237. Palatability of Foods. — Many foods naturally 
contain essential oils and other substances which im- 
part palatability. These have but little in the way of 
nutritive value, but they assist in rendering the nutri- 
ents with which they are associated more digestible. 
Palatability of a food favorably influences the secretion 
of the gastric and other digestive fluids, and in this way 
the natural flavors of well-prepared foods aid in diges- 
tion. In the feeding of farm animals it has been found 
that when foods are consumed with a relish better re- 
turns are secured than when unpalatable foods are fed. 
To secure palatability the excessive use of condiments 
is unnecessary. It is possible to a great extent during 
preparation to develop and conserve the natural flavors. 
Some foods contain bitter principles which are removed 
during the cooking, while in others pleasant flavors are 
developed. Palatability is an important factor in the 
digestibiUty of foods. 

238. Physiological Properties of Food. — Some food 
materials, particularly fruits and vegetables, contain 
compounds which have definite physiological properties, 
as tannin which is an astringent, special oils which 
exert a cathartic action, and the alkaloids which serve 
as irritants to nerve centers. Wheat germ oil is laxa- 
tive, and it is probable that the physiological properties 
of graham and whole wheat breads are due in some 



THE DIGESTIBILITY OF FOODS 229 

degree to the oil which they contain.^'' The use of 
fruits, herbs, and vegetables for medicinal purposes is 
based upon the presence of compounds possessing well- 
defined medicinal properties. As a rule food plants do 
not contain appreciable amounts of such substances, 
and the use of food for medicinal effect should be by 
the advice of a physician. The physiological proper- 
ties of some foods are due to bacterial products. See 
Chapter XX. 

239. Individuality. — Material difference in digestive 
power is noticeable among individuals. Digestion ex- 
periments show that one person may digest 5 per cent 
more of a nutrient than another. This difference ap- 
pears to be due to a number of factors, as activity of 
the organs, as affected by exercise and kind of labor 
performed ; abnormal composition of the digestive 
fluids ; or failure of the different parts of the digestive 
tract to act in harmony. Individuality is one of the 
most important factors in digestion. Persons become 
accustomed to certain foods through long usage, and 
the digestive tract adapts itself to those foods, render- 
ing sudden and extreme changes in the dietary hazard- 
ous. Common food articles may fail to properly digest 
in the case of some individuals, while with others they 
are consumed with benefit. What is food to one may 
prove to be a poison to another, and while general 
statements can be made in regard to the digestibility of 
foods, individual differences must be recognized. 



230 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

240. Psychological Factors. — Previously conceived 
ideas concerning foods influence digestibility. Foods 
must be consumed with a relish in order to secure the 
best results, as flow of the digestive fluids and activity 
of the organs are to a certain extent dependent upon 
the nerve centers. If it is believed that a food is 
poisonous or injurious, even when the food is whole- 
some, normal digestion fails to take place. In ex- 
periments by the author, in which the comparative 
digestibility of butter and oleomargarine was being 
studied, it was found that when the subjects were told 
they were eating oleomargarine, its digestibility was de- 
pressed 5 per cent, and when they were not told the 
nature of the material, but assumed that butter was 
oleomargarine, the digestibility of the butter was low- 
ered about 6 per cent.^^ Preconceived notions in regard 
to foods, not founded upon well-established facts, but 
due to prejudice resulting from ignorance, cause many 
valuable foods to be excluded from the dietary. Many 
persons, like the foreign lady who, visiting this country, 
said she ate only acquaintances, prefer foods that have 
a famihar taste and appearance, and any unusual taste 
or appearance detracts from the value because of the 
psychological influence upon digestion. 



CHAPTER XVI 
COMPARATIVE COST AND VALUE OF FOODS 

241. Cost and Nutrient Content of Foods. — The mar- 
ket price and the nutritive value of foods are often at 
variance, as those which cost the most frequently con- 
tain the least nutrients.'^ It is difficult to make abso- 
lute comparisons as to the nutritive value of foods at 
different prices, because they differ not only in the 
amounts, but also in the kinds of nutrients. While it is 
not possible to express definitely the value of one food 
in terms of another, approximate comparisons may be 
made as to the amounts of nutrients that can be se- 
cured for a given sum of money when foods are at dif- 
ferent prices, and tables have been prepared making 
such comparisons. 

242. Nutrients Procurable for a Given Sum.^ — To as- 
certain the nutrients procurable for a given sum first 
determine the amount in pounds that can be obtained, 
say, for ten cents, and then multiply by the percentages 
of fat, protein, carbohydrates, and calories in the food. 
The results are the amounts, in pounds, of nutrients 
procurable for that sum of money. For example: if 

231 



232 



HUMAN FOODS AND THEIR NUTRITIVE VALUE 



FOOD AM) Diirr 

Chan i>.-Hli,\irosiTH)N !)1" I'oii!) M,\Ti:i(lAi>. 



M Tiui.Ms. Ki.i I si:, a.m> I ri;i, \ \i,( i:. 

filial M^ ■ NoNMTlilKM- nil. Ml,i tl 



10 20 30 40 50 60 70 80 90 
400 800 1200 1600 ZOOO 2400 ZBOO 3200 3600 



Beet round 
Beet round ' 
Beef iarloin 
Beef, arloin ' 
Beelnb 
Beelnb' 
Muttoa leg 
Pork, spare rib 
Pork, salt 



Ham.: 

Codfisk fresh 

Codfish, salt 

Oysters 

Milk 

Butter 

Cheese 

te 

Wheat bread 
Wheat flour 
Cora meal 
Oatmeal 
Beans, dned 
Rice 

Potatoes 
Sugar 



Fig. 56. — Composition of Foods. 
(From Office of Experiment Stations Bulletin.) 



COMPARATIVE COST AND VALUE OF FOODS 233 

milk is 5 cents per quart, two quarts or approximately 
four pounds, can be procured for lo cents. If the milk 
contain fat, 4 per cent, protein, 3.3 per cent, carbo- 
hydrates, 5 per cent, and fuel value, 310 calories per 
pound, multiplying each of these by 4 gives the nutri- 
ents and fuel value in four pounds, or 10 cents worth 
of milk, as follows: 

Protein 0.13 Ibr. 

Fat 0.16 lb. 

Carbohydrates 0.2 lb. 

Calories 1240 

If it is desired to compare milk at 5 cents per quart 
with round steak at 15 cents per pound, 10 cents will 
procure 0.66, or two thirds of a pound of round steak 
containing on an average (edible portion) 19 per cent 
protein, 12.8 per cent fat, and yielding 890 calories per 
pound. If 10 per cent is refuse, there is edible about 
0.6 of a pound. The amounts of nutrients in the 0.6 of 
a pound of steak, edible portion, or 0.66 lb. as pur- 
chased would be : 

Protein o.ii lb. 

Fat 0.08 lb. 

Calories 534 

It is to be observed that from the 10 cents' worth of 
milk a little more protein, 0.08 of a pound more fat, and 
nearly two and one half times as many calories can be 
secured as from the 10 cents' worth of meat. This is 
due to the carbohydrates and the larger amount of fat 



234 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

which the milk contains. At these prices, milk should 
be used liberally in the dietary, as it furnishes more of 
all the nutrients than does meat. It would not be ad- 
visable to exclude meat entirely from the ration, but 
milk at 5 cents per quart is cheaper food than meat at 
15 cents per pound. In making comparisons, prefer- 
ence cannot always be given to one food because of its 
containing more of any particular nutrient, for often 
there are other factors that influence the value. 

243. Comparing Foods as to Nutritive Value. — In 
general, preference should be given to foods which sup- 
ply the most protein, provided the differences between 
the carbohydrates and fats are not large. When the 
protein content of two foods is nearly the same, but the 
fats and carbohydrates differ materially, the preference 
may safely be given to the food which supplies the 
larger amount of total nutrients. A pound of protein 
in a ration is more valuable than a pound of either fat 
or carbohydrates, although it is not possible to establish 
an absolute scale as to the comparative value of these 
nutrients, because they serve different functional pur- 
poses in the body. It is sometimes necessary to use 
small amounts of foods rich in protein in order to se- 
cure a balanced ration ; excessive use of protein, how- 
ever, is not economical, as that which is not needed for 
functional purposes is converted into heat and energy 
which could be supplied as well by the carbohydrates, 
and they are less expensive nutrients. 



FOOD AM) Diirr. 



Aiiioinits of Xiitii.'iits ()l>tiiiii(Ml ill Diir.niil loud Miit.iiiiN l.n- |0 ..i 

IVnlrin |-;,K. ( .„l„.l,Mh.,t.- 1',>..|, Min.n.l 



r.-i, 

ntsHill l'..iiniK..riuitii.-.i1.i.(HtMl. 



ILb. 2Lb& 3Lbs^ 4 Lbs. 
2000 Cal. 4000 Cal. 6000 Cal. 8000 Cal, 



M round 12 ,83 i 

M sirloin 18 .55 i 

Beef, rib 16 .63^ 

Mutton, leg 12 .83^ 

Pork, spare rib 12 .83 JI 

Pork, salt fat 14 .71 = 

Ham. smoked 16 .63 ± 

Codfish, fresh 8 125 . 

Codfish, salt 6 1.67 -i 

Oysters. 40 cfeqt. 20 .50 1 

Milk.6cts.qt. 3 3.33 i 

Butter 24 .42 S 

Cheese 16 .63 wZ 

Egp. 25 ct^. doz. m .60 i 

Wheat bread 4 2.50 mL, 

Wheat flour Z' '^00 _ 

Com meal 2 5,00 mi 

Oatmeal 4 Z.50 _ 

Beans, white, dried 4 2,50 i^ 

Rice 5 2,00 il. 

PoUtoes.60ctsbush, 1 10,00^ 

Sugar 5 2.00 _ 



Fig. 57. — Pecuniary Economy of Food. 

(From Office of Experiment Stations BuUetin.) 

235 



236 HUMAN FOODS AND THEIR NUTRITIVE VALUE 



Ten Cents will Purchase : 

(From Farmer's Bulletin No. 142, U. S. Dept. of Agr.) 



Kind of Food Material 



Beef, sirloin 

Do 

Do 

Beef, round 

Do 

Do 

Beef, shoulder clod .... 

Do 

Beef, stew meat 

Beef, dried, chipped .... 

Mutton chops, loin 

Mutton, leg 

Do 

Roast pork, loin 

Pork, smoked ham .... 

Do 

Pork, fat salt 

Codfish, dressed, fresh . . . 

Halibut, fresh 

Cod, salt 

Mackerel, salt, dressed . . . 

Salmon, canned 

Oysters, solids, 50 cents per quart 
Oysters, solids, 35 cents per quart 

Lobster, canned 

Butter 

Do 

Do 

Eggs, 36 cents per dozen . . 
Eggs, 24 cents per dozen . . 
Eggs, J 2 cents per dozen . . 

Cheese 

Milk, 7 cents per quart . . . 
Milk, 6 cents per quart . . . 
Wheat flour 

Do 

Corn meal, granular .... 
Wheat breakfast food . . . 

Oat breakfast food 

Oatmeal 

Rice 

Wheat bread 

Do 

Do 

Rye bread . . . . . . . •. 

Beans, white, dried .... 



Price 

. PER 

Pound 



Cents 

25 

20 

15 

16 

14 

12 
12 
9 

5 

25 
16 
20 
16 
12 
22 
18 
12 
10 
18 

7 
10 
12 

25 
18 
18 
20 
25 
30 
24 
16 
8 
16 

3k 

3 

3 

2.V 

H 

7\ 

4 

8 
6 

5 
4 

5 • 

5 



Total 
Weight 
OF Food 

Mate 

RIAL 



Pounds 
0.40 
0.50 
0.67 
0.63 
0.71 
0.83 
083 
I. II 
2.00 
0.40 
0.63 
0.50 
0.63 
0.83 

0-45 
0.56 
0.83 
1. 00 
0.56 

1-43 
1. 00 
0.83 
0.40 
0.56 
0.56 
0.50 
0.40 

0-33 
0.42 
0.63 

1-25 
0.63 
2.85 
3-33 
3-33 
4.00 
4.00 
1-33 
1-33 
2.50 
1.25 
1.67 
2.00 
2 50 
2.00 
2.00 



Pro- 
tein 



Pound 
0.06 
0.08 
o.IO 
O.II 

0.13 

o.is 
o 13 

0.18 
0.29 
0,10 
0.08 
0.07 
0.09 

O.II 

o.g6 

0.08 
o 02 

O.II 

0.08 

0.22 

0.13 
0.18 

0.02 

0.03 

O.IO 
O.OI 



0.05 
0.07 
0.14 
0.16 
0.09 

O.II 

0.32 

0.39 
0.31 
0.13 
0.19 

0-34 
0.08 
0.13 
0.16 
0.20 
O.IS 
0.35 



Fat 



Pound 
0.06 
0.08 
O.II 
0.08 
0.09 
O.IO 

0.08 

O.IO 

0.23 
0.03 
0.17 
0.07 
C.09 
0.19 
0.14 
0.18 
0.68 

0.02 

O.OI 

0.20 

O.IO 
O.OI 

o 01 
0.40 
0.32 

0.27 
0.04 
0.06 

O.II 

0.20 

O.II 

0.13 

0.03 

0.04 
0.07 
0.02 
0.09 
0.16 

0.02 
0.02 
0.03 

O.OI 

0.03 



Car- 
bohy- 
drates 



Pounds 



O.OI 

O 02 



0.02 
0.14 
0.17 

2-45 
2.94 
2.96 
0.98 
0.86 
1.66 
0.97 
0.87 
1.04 
I 30 
I 04 
1. 16 



COMPARATIVE COST AND VALUE OF FOODS 



237 



Kind of Food Material 



Price 

PER 

Pound 



Total 








Weight 

OF Food 

Mate- 


Pro- 
tein 


Fat 


Car- 

BOHY- 

dr.\tes 


rial 








4.00 


0.05 


O.OI 


0.18 


2.00 


0.02 


— 


0.05 


1. 00 


0.02 


O.OI 


0.18 


6.67 


O.IO 


O.OI 


0.93 


10.00 


0.15 


O.OI 


1.40 


1333 
10.00 


0.20 
0.08 


O.OI 
O.OI 


1.87 

0.54 


6.67 


0.02 


0.02 


0.65 


1-43 


O.OI 


O.OI 


0.18 


1.67 


O.OT 


— 


0.13 


1-43 
1.67 


.01 


O.OI 


0.09 

1.67 



Energy 



Cabbage 

Celery 

Corn, canned 

Potatoes, 90 cents per bushel 
Potatoes, 60 cents per bushel 
Potatoes, 45 cents per bushel 

Turnips 

Apples 

Bananas 

Oranges 

Strawberries 

Sugar 



25 

5 

10 
ih 

I 
I 
I 

I5 
7' 
6 

7 



460 
130 

430 
1970 
2950 

3935 

1200 

1270 

370 

250 

215 
2920 



It is to be noted in the table that, ordinarily, for the 
same amount of money the most nutrients can be ob- 
tained in the form of milk, cheese, sugar, and beans, corn 
meal, wheat flour, oatmeal, and cereals in bulk. While 
meats supply protein liberally, they fail to furnish car- 
bohydrates as the vegetables. As discussed ia the 
chapter oq Dietary Studies of Families, unnecessarily 
expensive foods are often used, resulting either in lack 
of nutrients or unbalanced rations. 



EXAMPLES 

1. Compute the calories and the amounts of protein, fat, and car- 
bohydrates that can be procured for 25 cents in cheese selling for 
18 cents per pound ; how do these compare with the nutrients in 
eggs at 20 cents per dozen ? 

2. Which food furnishes the larger amount of nutrients, potatoes 
at 50 cents per bushel or flour at $6 per barrel ? 

3. How do beans at 10 cents per quart compare in nutritive value 
with beef at 15 cents per pound ? 

4. How does salt codfish at 10 cents per pound coinpare in nu- 
tritive value with lamb chops at 15 cents per pound ? 

5. Compare in nutritive value cream at 25 cents per quart with 
butter at 30 cents per pound. 

6. Calculate the'composition and nutritive value of a cake made 
of sugar, 8 oz. ; butter, 4 oz. ; eggs, 8 oz. ; flour, 8 oz. ; and milk, 
4 oz. ; the baked cake weighs one and three fourths pounds. 



238 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

Average Composition of Common American Food 
Products 

(From Farmer's Bulletin, No. 142, U. S. Dept. of Agr.) 



Food Materials (as purchased) 



ANIMAL FOOD 

Beef, fresh : 

Chuck ribs 

Flank 

Loin 

Porterhouse steak 

Sirloin steak 

Neck 

Ribs 

Rib rolls 

Round 

Rump 

Shank, fore 

Shoulder and clod 

Fore quarter 

Hind quarter 

Beef, corned, canned, pickled, dried 

Corned beef 

Tongue, pickled 

Dried, salted, and smoked 

Canned boiled beef 

Canned corned beef 

Veal: 

Breast 

Leg 

Leg cutlets 

Fore quarter 

Hind quarter 

Mutton : 

Flank 

Leg, hind 

Loin chops 

Fore quarter 

Hind quarter, without tallow . . . . 
Lamb : 

Breast 

Leg, hind 



% 

16.3 
10.2 

133 
12.7 
12.8 
27.6 
20.8 

7.2 
20.7 

36.9 
16.4 
18.7 
15-7 

8.4 
6.0 
4-7 



21.3 
14.2 
34 
24-5 
20.7 

9.9 
18.4 
16.0 
21.2 
17.2 

19.1 
174 



% 
52.6 
54-0 
52.5 
524 
54-0 
45-9 
43-8 
63-9 
60.7 

45-0 
42.9 
56.8 
49.1 
504 

49.2 
58.9 
53-7 
51-8 
51.8 

52.0 
60.1 
68.3 
54-2 
56.2 

39-0 
51-2 
42.0 
41.6 
454 

45-5 
52.9 



% 

15-5 
17.0 
16.1 
19.1 
16.5 
14-5 
13-9 
19-3 
19.0 
13-8 

T2.8 
16.4 

14-5 
154 

14-3 
11.9 
26.4 

25-5 
26.3 

154 
15-5 
20.1 

I5-I 
16.2 

13-8 
I5-I 
13-5 
12.3 

13-8 

154 
159 



15.0 
19.0 

17-5 
17.9 
16. 1 
11.9 
21.2 
16.7 
12.8 
20.2 

7-3 
9.8 

17-5 
18.3 

23.8 
19.2 
6.9 
22.5 
18.7 

li.o 
7-9 

7-5 
6.0 
6.6 

36.9 
14.7 
28.3 

24-5 
23.2 

19. 1 
13.6 



% 



COMPARATIVE COST AND VALUE OF FOODS 



239 



Average Composition of Common American Food 
Products — Continued 



Food Materials (as purchased) 



ANIMAL FOOD COHtlJlUed 

Pork, fresh : 

Ham 

Loin chops , 

Shoulder 

Tenderloin 

Pork, salted, cured, pickled : 

Ham, smoked 

Shoulder, smoked 

Salt pork 

Bacon, smoked 

Sausage : 

Bologna 

Pork 

Frankfort 

Soups : 

Celery, cream of 

Beef.'. 

Meat stew 

Tomato 

Poultry : 

Chicken, broilers 

Fowls 

Goose 

Turkey 

Fish : 

Cod, dressed 

Halibut, steaks or sections . 

Mackerel, whole 

Perch, yellow dressed 

Shad, whole 

Shad, roe , 

Fish, preserved : 

Cod, salt 

Herring, smoked 

Fish, canned 

Salmon , 

Sardines 



% 

10.7 
19.7 
12.4 



13-6 
18.2 

1-1 
33 



41.6 

25-9 
17.6 
22.7 

29.9 
17.7 
44-7 
35-1 
50.1 



24.9 
44-4 



*5.o 



% 

48.0 
41.8 
44.9 
66.5 

34-8 
36.8 

7-9 
17.4 

55-2 
39-8 
57-2 

88.6 
92.9 

84-5 
90.0 

43-7 

47.1 

38.5 
42.4 

58.S 
61.9 
40.4 
50-7 
35-2 
71.2 

40.2 
19.2 

63-5 
53-6 



% 
135 
13-4 
12.0 
18.9 

14.2 

13.0 

1.9 

9.1 

18.2 
13.0 
19.6 

2.1 

4.4 
4.6 
1.8 

12.8 

13-4 
i6.i 

II. I 

15-3 
10.2 
12.8 
9.4 
20.9 

16.0 
20.5 

21.8 
23-7 



% 

25-9 
24.2 
29.8 
13.0 

334 
26.6 
86.2 
62.2 

19.7 
44.2 
18.6 

2.8 
0.4 

4-3 
I.I 

1.4 
12.3 
29.8 
18.4 

0.2 

4-4 
4.2 
C.7 
4.8 
3-8 

0.4 



12. 1 
12. 1 



I.I 
I.I 

5-0 
I.I 

5-5 
5-6 



2.6 



7o 

0.8 

0.8 

0.7 

i.o 

4.2 
5-5 
3-9 
4.1 

3-8 
2.2 

3-4 

1-5 
1.2 
I.I 
1-5 

0.7 
0.7 
0.7 
0.8 

0.8 
0.9 
0.7 
0.9 
0.7 
1-5 

18.5 
7-4 

2.6 

5-3 



* Refuse, oil. 



240 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

Average Composition of Common American Food 
Products — Continued 



Food Materials (as purchased) 



ANIMAL FOOD COHltnued 

Shellfish : 

Oysters, solids 

Clams 

Crabs 

Lobsters 

Eggs: Hen's eggs 

Dairy products, etc. : 

Butter 

Whole milk 

Skim milk 

Buttermilk 

Condensed milk 

Cream 

Cheese, Cheddar 

Cheese, full cream 

VEGETABLE FOOD 

Flour, meal, etc. : 

Entire wheat flour 

Graham flour 

Wheat flour, patent roller process 

High-grade and medium 

Low grade 

Macaroni, vermicelli, etc , 

Wheat breakfast food 

Buckwheat flour 

Rye flour 

Corn meal 

Oat breakfast food 

Rice 

Tapioca , 

Starch 

Bread, pastry, etc. : 

White bread 

Brown bread 



52.4 
61.7 
II. 2 



% 
88.3 
80.8 
36-7 
30.7 
65-5 

II. o 

87.0 

90-5 
91.0 
26.9 
74.0 
27.4 
34-2 



11.4 
"3 

12 o 
12.0 
10.3 

9.6 
13.6 
12.9 
12.S 

7-7 
12.3 
11.4 



35-3 
43-6 



% 

6.0 
10.6 

7-9 

5-9 
131 



3-3 
3-4 
30 

8.8 

2-5 

27.7 

25-9 



13.8 
13-3 

11.4 
14.0 

134 
12. 1 
6.4 
6.8 
9.2 
16 7 
8.0 
0.4 



9.2 
5-4 





K X 
< Q 


% 


% 


1-3 


3-3 


I.I 


5-2 


0.9 


0.6 


0.7 


0.2 


9-3 


— 


85.0 


— 


4.0 


S-o 


0-3 


S-i 


o-.S 


4.8 


.8.1 
36.8 


541 
4-5 
4.1 


33-7 


2.4 


1-9 


71.9 


2.2 


71.4 



I.O 

1.9 
0.9 

1.8 
1.2 
0.9 
1.9 
7-3 
03 
o.i 



75-1 
71.2 
74.1 
75-2 
77-9 
78.7 

75-4 
66.2 
79.0 
88.0 
90.0 

53-1 
47.1 



% 

I.I 

23 

1-5 

0.8 

.09 

30 
0.7 
0.7 
0.7 
1.9 

0-5 
4.0 
3.8 



i.o 

1.8 

05 
0.9 

13 
1-3 
0.9 
0.7 
I Q 
2.1 

0.4 

C.I 



I.I 
2.1 



* Refuse, shell. 



COMPARATIVE COST AND VALUE OF FOODS 



241 



Average Composition of Common American Food 
Products — Continued 



Food Materials (as purchased) 



VEGETABLE FOOD — Continued 

Bread, pastry, etc. : 

Graham bread 

Whole wheat bread 

Rye bread 

Cake 

Cream crackers 

Oyster crackers 

Soda crackers 

Sugars, etc. : 

Molasses 

Candy * 

Honey 

Sugar, granulated 

Maple sirup 

Vegetables : t 

Beans, dried 

Beans, IJma, shelled 

Beans, string 

Beets 

Cabbage 

Celery 

Corn, green (sweet) , edible portion 

Cucumbers 

Lettuce 

Mushrooms 

Onions 

Parsnips 

Peas {Pisiim safivuiii), dried 

Peas {Pisiim sativum), shelled. . . . 

Cowpeas, dried 

Potatoes 



% 



70 
20.0 

150 
20.0 

15.0 
15.0 

10. o 
20 o 



% 

35-7 

38.4 

35-7 

19.9 

6.8 

4.8 

5-9 



12.6 

68.5 
83.0 
70.0 
77-7 
75-6 
75-4 
81. 1 
80.5 
88.1 
78.9 
66.4 

9-5 
74.6 
13.0 
62.6 



% 
8.9 
9-7 
9.0 

6.3 

9-7 

II-3 

9.b 



22.5 

7-1 
2.1 

1-3 
1.4 
0.9 

3-1 
0.7 
i.o 

35 
1.4 

1-3 
24.6 

7.0 
21.4 

1.8 



1.8 
0.9 
0.6 
9.0 
12. 1 
10.5 
9.1 



1.8 
0.7 

0.3 
o.i 
0.2 
0.1 
I.I 
0.2 
0.2 
0.4 

0-3 
0.4 
1.0 

0-5 
1.4 
0.1 



% 
52.1 
49-7 
53-2 
63-3 
69.7 

70s 
73-1 

70.0 
96.0 
81.0 
1 00.0 
71.4 

59-6 

22.0 

6.9 

7-7 
4.8 
2.6 
19.7 
2.6 

2-5 

6.8 
8.9 
10.8 
62.0 
16.9 
60.8 
14.7 



% 

i-S 

1-3 

1-5 

1-5 

1.7 

2,9 

2.1 



3-5 
1-7 
0.7 
0.9 
0.9 
0.8 
0.7 
0.4 
0.8 
1.2 

o-S 
I.I 
2.9 
1.0 

3-4 
0.8 



Calo- 
ries 

1 195 
1 130 
1 170 
1630 
1925 
I910 

1875 

1225 
1680 
1420 
1750 
1250 

1520 
'540 
170 
160 
115 
65 
440 

65 

65 

185 

190 

230 

1565 
440 

1505 
295 



* Plain confectionery not containing nuts, fruit, or chocolate. 

t Such vegetables as potatoes, squash, beets, etc., have a certain amount of inedible 
material, skin, seeds, etc. The amount varies with the method of preparing the vege- 
tables, and cannot be accurately estimated. The figures given for refuse of vegetables, 
fruits, etc., are assumed to represent approximately the amount of refuse in these foods 
as ordinarily prepared. 



242 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

Average Composition of Common American Food 
Products — Continued 



Food Materials (as purchased) 



VEGETABLE FOOD — COtlthlUed 

Vegetables : 

Rhubarb 

Sweet potatoes 

Spinach 

Squash 

Tomatoes 

Turnips 

Vegetables, canned : 

Baked beans 

Peas {Pisum sativum), green 

Corn, green 

Succotash 

Tomatoes 

Fruits, berries, etc., fresh : * 

Apples 

Bananas 

Grapes 

Lemons 

Muskmelons 

Oranges 

Pears 

Persimmons, edible portion . 

Raspberries 

Strawberries 

Watermelons 

Fruits, dried : 

Apples 

Apricots 

Dates 



% 
40,0 
20 o 

50.0 

30.0 



25.0 
35 -o 
25.0 
30.0 
50.0 
27.0 
10. o 



50 

59-4 



70 
56.6 
55-2 
92.3 
44.2 

94-3 
62.7 

68.9 

85-3 
76.1 

75-9 
94.0 

633 
48.9 
58 .o 
62.5 
44.8 

634 
76.0 
66.1 
85.8 
85-9 
37-5 

28.1 
29.4 
13.8 



% 

0.4 

1.4 

2.1 

0.7 

0.9 

0.9 

6.9 
3-6 
2.8 
3-6 
1.2 



0.3 
0.8 
i.o 
0.7 

0.3 
0.6 

0-5 
0.8 
1.0 
0.9 



1.6 

4-7 
1.9 



% 

0.4 

0.6 

0-3 
0.2 
0.4 
0.1 



2.5 

0.2 

1.2 
1.0 
0.2 

0.3 
0.4 
1.2 

0.5 

O.I 
0.4 
0.7 

0.6 
O.I 



% 

2.2 

21.9 

3-2 

4-5 
3-9 

5-7 

19.6 
9.8 
19.0 
18.6 
4.0 

10.8 

143 
14.4 

5-9 
4.6 

8.5 
12.7 

315 

12.6 

7.0 

2.7 



2.2 66.1 
1.0 62.5 
2.5 70.6 

i 



% 

0.4 

0.9 

2.1 

0.4 

0.5 
0.6 

2.1 
I.I 
0.9 
0.9 
0.6 

0.3 
0.6 
0.4 
0.4 

0.3 
0.4 
0.4 
0.9 
0.6 
0.6 
0.1 

2.0 
2.4 



Calo- 
ries 
60 
440 

95 
ICO 
ICO 

120 

555 
235 
430 
425 
95 

190 
260 
295 
125 
80 

150 
230 

550 
220 

150 

50 

1185 
1 125 

1275 



* Fruits contain a certain proportion of inedible materials, as skin, seeds, etc., which 
are properly classed as refuse. In some fruits, as oranges and prunes, the amount 
rejected in eating is practically the same as retuse. In others, as apples and pears, 
more or less of the edible material is ordinarily rejected with the skin and seeds and 
other inedible portions. The edible material whicfi is thus thrown away, and should 
properly be classed with the waste, is here classed with the refuse. The figures for 
refuse here given represent, as nearly as can be ascertained, the quantities ordinarily 
rejected. 



COMPARATIVE COST AND VALUE OF FOODS 



243 



Average Composition of Common American Food 
Products — Continued 



Food Materials (as purchased) 



u 




7, 


p 













p^ 


^ 


&H 


% 


% 


% 


— 


18.8 


4-3 


10. 


I3-I 


2.3 


45 -o 


2.7 


1 1 -5 


49.6 


2.6 


8.6 


86.4 


0.6 


3.8 


16.0 


37.a 


5.2 


24.0 


4-5 


8.1 


*48.8 


7.2 


2.9 


— 


3-5 


(^•3 


52.1 


1.8 


7-5 


62.2 


1.4 


5.« 


53-2 


1.4 


5-2 


24-5 


6.9 


19-5 


40.6 


2.0 


8.7 


74.1 


0.6 


7.2 


58.1 


I.O 


6.9 





5-9 


12.9 


— 


4.6 


21.6 


- 


98.2 


0,2 







< u 












K S 




< n 


< 


CJ > 




I 




% 


% 


74.2 


2.4 


68.5 


3-1 


9-5 


I.I 1 


3-5 


2.0 


0-5 


0.4 


35-4 


I.I 


5(>4 


1-7 


143 


0.9 


31-5 


1-3 


6.2 


I.I 


4-3 


0.8 


6.2 


0.7 


18.5 


1-5 


10.2 


1-7 


3-0 


0.5 


6.8 


0.6 


30-3 


2.2 


37-7 


7.2 


1-4 


0.2 



^ 9 

< 3 
►> o 



VEGETABLE FOOD — COUtitUted 

Fruits, dried : 

Figs 

Raisins 

Nuts: 

Almonds 

Brazil nuts 

Butternuts 

Chestnuts, fresh 

Chestnuts, dried 

Cocoanuts 

Cocoanut, prepared 

Filberts 

Hickory nuts 

Pecans, polished 

Peanuts 

Pinon {Pitttis edulis) 

Walnuts, black 

Walnuts, English 

Miscellaneous : 

Chocolate , 

Cocoa, powdered 

Cereal coffee, infusion (i part 
boiled in 20 parts water) f 



% 
0-3 
30 

30.2 

33-7 

8.3 

4-5 

5-3 

25-9 

57-4 

31-3 

25-5 

33-3 

29.1 

36.8 

14.6 

26.6 

48.7 
28.9 



Calo- 
ries 

1280 
1265 

15^5 
1485 
385 
915 
1385 
1295 
2865 

1430 
II45 
1465 
1775 
1730 
730 
1250 

5625 
2160 

30 



* Milk and shell. 

t The average of five analyses of cereal coffee grain is : Water 6.2, protein 13.3, fat 
3.4, carbohydrates 72.6, and ash 4.5 per cent. Only a portion of the nutrients, however, 
enter into the infusion. The average in the table represents the available nutrients in the 
beverage. Infusions of genuine coffee and of tea like the above contain practically no 
nutrients. 



CHAPTER XVII 
DIETARY STUDIES 

244. Object of Dietary Studies. — The quantity of food 
which different families purchase varies between wide 
limits ; a portion being lost mechanically in preparation 
and a still larger and more variable amount in the ref- 
use and non-edible parts. If a record is made of all 
foods purchased and the waste and non-edible portions 
are deducted, the nutrients consumed by a family may 
be calculated by multiplying the weight of each food 
by the average composition. If such calculations be 
made, it will be found that in some families nearly a 
half pound per day of both protein and fat is consumed 
by adults, while in other famiUes less than half of this 
amount is used. The object of dietary studies is to de- 
termine the source, cost, composition, and nutritive value 
of the foods consumed by different families; they also 
enable comparisons to be made of the amounts of nu- 
trients purchased. Extensive dietary studies have been 
made by the United States Department of Agriculture, 
and the results have been pubHshed in various bulletins.'^ 

245. Wide and Narrow Rations. — When the amount 
of carbohydrates in a ration is small in comparison with 
the protein, it is called a narrow ration, while a wide 
ration is one in which the carbohydrates are much in ex- 

244 



DIETARY STUDIES 245 

cess of the protein. When a ration contains 0.40 of a 
pound of protein, 0.40 of a pound of fat, and i pound of 
carbohydrates, it has a nutritive ratio of i to 4.8 and is 
a narrow ration. To calculate the nutritive ratio, the 
fat is multiplied by 2|, the product added to the 
carbohydrates, and this sum divided by the protein. 
It is not possible to designate accurately the amount 
of protein and other nutrients that should be in the 
daily ration of all persons, because the needs of the 
body vary so with different individuals. Hard and fast 
rules governing the amounts of nutrients to be consumed 
cannot as yet be formulated, as our knowledge of the 
subject is too hmited. It is known that both excessive 
and scant amounts are alike injurious. While the appe- 
tite may indicate either hunger or satiety, it alone can- 
not always be relied upon as a safe guide for determining 
the amount and kind of food to consume, although the 
demands of appetite should not be disregarded until it 
has been demonstrated beyond a doubt that it is not 
voicing the needs of nature. There has been a tendency 
which perhaps was a survival of the Puritanical ideas 
of the early days to stamp as hurtful whatever seemed 
desirable and pleasant ; as examples might be cited the 
craving for water by fever patients, and for sugar by 
growing children, which have now been proven to be 
normal demands of nature. 

246. Dietary Standards. — As a result of a large num- 
ber of dietary studies and digestion experiments, dietary 



246 



HUMAN FOODS AND THEIR NUTRITIVE VALUE 



standards have been prepared. Atwater in this coun- 
try and Voit in Germany have proposed such standards 
for men employed at different kinds of labor, as follows : 





lb. 


lb. 


6 ° 




> 




lb. 


Calories 


Ratio 


Man with little physical exercise . 


0.20 


0.20 


0.66 


2450 


5-5 


Man with light muscular work . . 


0.22 


0.22 


0.77 


2800 


5-7 


Man with moderate muscular work 


0.28 


0.28 


099 


3520 


5.8 


Man with active muscular work . 


0-33 


0.33 


1. 10 


4060 


5.6 


Man with hard muscular work . 


0-39 


0.55 


143 


5700 


6.9 



In the table it will be seen that the quantity of nu- 
trients increases with the labor to be performed. In 
order to secure the necessary heat and energy, rations 
for men at heavy labor contain proportionally more 
fat and carbohydrates than are required for light work. 
All dietary standards, however, should be regarded as 
tentative only. Opinions differ greatly on different 
points ; for example, as to the amount of protein a ration 
should contain. This is a matter that can be deter- 
mined only from extended investigations under a variety 
of conditions, and as yet results are too meager to for- 
mulate other than tentative standards. Chittenden has 
found that the body can be sustained on very much 
less protein than is called for in the standard ration.'^ 
The amount of protein in the ration should be ample 
to sustain the body weight and maintain a nitrogen 



FOOD AM) Diirr. 

ohart 4-inri'Aini:s and ihktaim stamiakiis. 



\i ii,ir,M^ \\ii i:\ri 



Underfed laborei^ Italy 
Students, Japan 
Lawyer. Gei'inany 
Physician, Germany 
Physician. Denmark 
Well-fed tailor. Enojland 
Laborers at active work, En2;land 
Well-paid mechanics, Germany 
Miners at severe work, Prussia 
Mechamcs at moderate work, Sweden 
Mechanics at severe work, Sweden 
Chemist Connecticut 
Colleo'e professor, Connecticut 
College students. Northern States 
Mason, Connecticut 
Glassblower, Massachusett5 
Blacksmith, Connecticut 
Factory operativ&s, Massachusetts 
Brickmaker at hard work, Massachusetts 
Machinist at hard work. Mamchusetts 

iMohllV ^l:llHlil^<^. 

Man with httle muscular work 
Man at moderate work 
Man at severe work 



ILh 


2Lb& 


3 Lbs. 
6000 Cal. 


2000 Cal, 


4000 Cal, 


rnmrn 






**^" 






aaaa^ 


■ 


m$m 


m^mm 


ssm 


■ 


-^^ 


HM^ 


<«. 


" 


■IMIIMII 






SSLm^^m 


■™^^^^^ 


_. 




mSSSSm^^^^ 


'^"" H 


^^■B 






oa^ 


- 


[IjlH^. . 


:.^ 


— 




r-^^mmm 




K .1^ 


• 


— f 


r: ■- 




.... 


~^ 



Fig. 58. — Dietaries and Dietary Standards. 

(From Office of Experiment Stations Bulletin.) 

247 



248 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

equilibrium ; that is, the income and outgo of nitrogen 
from the body should be practically equal. 

''While one freely admits that health and a large measure of 
muscular strength may be maintained upon a minimum supply of 
protein, yet I think that a dispassionate survey of mankind will show 
that races which adopt such a diet are lacking in what, for want of a 
better word, one can only describe as energy.'" ^^ 

On the other hand, excessive and unnecessarily large 
amounts of protein are sometimes consumed, adding 
greatly to the cost of the ration and necessitating ad- 
ditional labor on the part of the body for its elimination. 

247. Number of Meals per Day. — Some persons ad- 
vocate two meals per day rather than three, but dietary 
studies show that the best results are secured when, 
the food is divided among three rather than two meals, 
and with a two-meal system the tendency is to con- 
sume a larger total amount of food than when three 
meals are eaten. It is not essential that the food be 
equally divided among the three meals. Any one of 
them may be lighter or more substantial as the habits 
and inclinations of the individual dictate. If it is found 
necessary to reduce the total quantity of food consumed, 
this may be done by a proportional reduction of each 
of the meals, or of any one of them instead of de- 
creasing the number of meals per day. The occasional 
missing of a meal is sometimes beneficial, in cases of 
digestion disorders, but the ordinary requirements of 
persons in normal health who have either mental or 



DIETARY STUDIES 249 

physical labor to perform are best met when three meals 
per day are consumed, as this insures an even supply of 
nutrients. For persons of sedentary habits, the kind 
and quantity of food at each meal must be regulated 
largely by the individual from knowledge based on 
personal experience. 

" In the matter of diet every man must, in the last resort, be a law 
unto himself; but he should draw up his dietetic code intelHgently 
and apply it honestly, giving due heed to the warnings which nature 
is sure to address to him should he at any time transgress." ^^ 

If there is trouble in digesting the food, it is well to 
study the other habits of life along with the food question, 
for it may be the difficulty arises from some other cause, 
and would be remedied by more exercise and fresh 
air, avoiding rush immediately after meals, more thorough 
mastication, or less worry. It is a serious matter to shut 
off the supply of food from a person not suffering from 
some disease and who is working ; as well cut off the 
supply of fuel from a furnace and then expect a full 
amount of energy and heat. But unlike the furnace, 
when the human body is deprived of needed nutrients 
it preys upon itself and uses up its reserve that should 
be drawn upon only in cases of illness or extreme 
nervous strain. Some persons live in such a way as 
to never have any reserve of strength and energy to 
call upon but use up each day all the body can pro- 
duce and so become physical bankrupts when they 
should be in their prime. Food is required for the 



250 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

production of nerve energy as well as physical en- 
ergy.'^ 

248. Mixed Dietary Desirable. — Experiments in the 
feeding of farm animals show that the best results come 
from the combination of a number of foods to form 
a mixed ration, rather than from the use of one food 
alone,'^ for in this way the work of digestion is more 
evenly distributed, and a higher degree of efficiency 
is secured from the foods consumed. The same is 
true in human feeding ; the best results are secured 
from a mixed diet. Ordinarily, about two fifths of the 
nutrients of a ration are derived from animal and three 
fifths from vegetable sources. 

249. Animal and Vegetable Foods; Economy of Pro- 
duction. — Animal foods can never compete in cheapness 
of the nutrients with cereals and vegetables, as it takes 
six to eight pounds or more of a cereal, together with 
forage crops, to make a pound of meat. Hence the re- 
turns in food value are very much larger from the direct 
use of the cereals as human food, than from the feeding 
of cereals to cattle and the use of the meat. As the 
population of a country increases, and foods necessarily 
become more. expensive, cereals are destined to replace 
animal foods to a great extent, solely as a matter of 
economy. 

250. Food Habits. — Long-established dietary habits 
and customs are not easily changed, and when the 
body becomes accustomed to certain foods, substitution 



DIETARY STUDIES 25 1 

of Others, although equally valuable, may fail to give 
satisfactory results. For example, immigrants from 
southern Europe demand foods with which they are 
familiar, as macaroni, olive oil, and certain kinds of 
cheese, foods which are generally imported and more 
expensive than the staples produced in this country,^^ 
and when they are compelled to live on other foods, 
even though they have as many nutrients, they complain 
of being underfed. Previously acquired food habits 
appear to affect materially the process of digestion and 
assimilation. Sudden and pronounced change in the 
feeding of farm animals is attended with unsatisfactory 
results, and whenever changes are made in the food of 
either humans or animals they should be gradual rather 
than radical. 

251. Underfed Families. — As the purchasing of food 
is often done by inexperienced persons, palatability 
rather than nutritive value is made the basis of choice. 
Dietary studies show that because of lack of knowl- 
edge of the nutritive value of foods, whole families are 
often underfed. Particularly is this true where the 
means for purchasing foods are limited. In dietary 
studies among poor families in New York City,^^ the 
United States Department of Agriculture notes : ** It 
is quite evident that what is needed among these 
families more than anything else is instruction in the 
way to make the little they have go the farthest." 
Some classes of the rich too are equally liable to be 



252 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

underfed, as they are more prone to food notions and 
are able to indulge them. Among the children of the 
rich are found some as poorly nourished as among the 
poor. 

252. Cheap and Expensive Foods. — Among the more 
expensive items of a ration are meats, butter, and canned 
fruits. The difference in composition and nutritive 
value between various cuts of meat is small, being 
largely physical, and affecting taste and flavor rather 
than nutritive value. Expensive cuts of meat, high- 
priced breakfast cereals, tropical fruits and foods which 
impart special flavors, add little in the way of nutritive 
value to the ration, but greatly enhance the cost of liv- 
ing. Ordinarily the cheapest foods are corn meal, wheat 
flour and bread, milk, beans, cheese, sugar, and pota- 
toes.' The amount of animal and vegetable foods to 
combine with these to form a balanced ration may be 
governed largely by personal preference or cost, as 
there is little difference in nutritive value. The selec- 
tion of foods on the basis of cost and nutritive value is 
discussed in Chapter XVI. 

25Z. Food Notions. — Many erroneous ideas exist as 
to the nutritive value of foods, and often wholesome and 
valuable foods are discriminated against because of 
prejudice. Skim milk is usually regarded as containing 
little if any nourishing material, when in reality it has a 
high protein content, and can be added to other foods 
to increase their nutritive value. The less expensive cuts 



DIETARY STUDIES 253 

of meat contain more total nutrients than many of the 
more expensive ones. Beef extracts have been errone- 
ously said to contain more nutrients than beef,^^ and 
mushrooms to be equal in value of beefsteak ; chemical 
analyses fail to confirm either statement. The banana 
also has been overestimated as to food value, and while 
it contains more nutrients than many fruits, it is not the 
equal of cereals, as has been claimed. ^^ Cocoa, although 
a valuable beverage, adds but Httle in the way of nu- 
trients to a ration unless it is made with milk. The 
value of a food should be based upon its composition 
as determined by chemical analysis, its digestibility as 
founded upon digestion experiments, and its palatability 
and mechanical structure. Food notions have, in many 
instances, been the cause of banishing from the dietary 
wholesome and nutritious foods, of greatly increasing 
the cost of living, as well as of promulgating incorrect 
ideas in regard to foods, so that individuals and in some 
cases entire families have suffered from improper or in- 
sufficient food. 

254. Dietary of Two Families Compared. — A dietary 
study often reveals ways in which it is possible to -im- 
prove the ration in kinds and amounts of food, and 
sometimes at less expense. The following dietaries of 
two families for the same period show that one family 
expends over twice as much in the purchase of foods as 
the other family, and yet the one whose food costs the 
less actually secures the larger amount of nutritive 



254 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

material and is better fed than the family where more 
money is expended for food.^^ 

Food Consumed, One Week 



Family No. i 



20 loaves of bread . . . $ i 00 
10 to 12 lb. loin steak, or 

meat of similar cost . . 2.00 
20 to 25 lb. rib roast, or 

similar meat .... 4.40 
4 lb. high-priced cereal 

breakfast food, 20 ct. . 0.80 

Cake and pastry purchased 3 .00 

8 lb. butter, 30 ct. . . . 2.40 

Tea, coffee, spices, etc. . 0.75 

Mushrooms 0.75 

Celery i.oo 

Oranges 2.00 

Potatoes 0.25 

Miscellaneous canned 

goods 2.00 

Milk 0.50 

Miscellaneous foods . . 2.00 

3 doz. eggs 0.60 



23-45 



Family No. 2 



15 lb. flour, bread home- 
made (skim milk used) $0.45 

Yeast, shortening and 

skim milk o.io 

10 lb. steak (round. Ham- 
burger, and some loin) 1.50 

10 lb. other meats, boil- 
ing pieces, nnnp roast, 

etc 1.00 

5 lb. cheese, 16 cents . . 0.80 

5 lb. oatmeal (bulk) . . 0.15 

5 lb. beans 0.23 

Home-made cake and 

pastry i.oo 

6 lb. butter, 30 ct. . . . 1.80 
3 lb. home-made shorten- 
ing 0.25 

Tea, coffee, and spices . 0.40 

Apples 0.50 

Prunes 0.25 

Potatoes ...... 0.25 

Milk I.oo 

Miscellaneous foods . . i.oo 

3 doz. eggs 0.60 

$11 .30 



DIETARY STUDIES 



255 



FAMILY No. I 



20 lb. bread 

10 lb. loin steak 

20 lb. rib roast 
.4 lb. cereals 
8 lb. butter 

25 lb. potatoes 

20 lb. milk 






VA'/WWWU//fM 



Protein .... 
Fat 

Carbohydrates 



FAMILY No. 2 



15 lb. flour 

5 lb. skim milk 
10 lb. round steak 
10 lb. beef 

5 lb. cheese 

5 lb. oatmeal 

6 lb. butter 

3 lb. shortening 

3 lb. prunes 
25 lb. apples 
25 lb. potatoes 
40 lb. milk 

5 lb. beans 



v////wu//M a 



xzzzzzzzzzzzzzn. 



Fig. 59. — Cost and Nutritive Value of Rations. 



In comparing the foods used by the two famiUes, it 
will be observed that family No. i purchased their bread 
at the bakery at a cost of $ i.oo, while the bread of 
family No. 2 was home-made, skim milk being used in 



256 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

its preparation, the flour, milk, yeast, and shortening cost- 
ing about 55 cents. Family No. i consumed 10 pounds 
of expensive steaks, family No. 2 consumed the same 
number of pounds, a portion being cheaper cuts. In- 
stead of the 20 pounds of roast or similar beef used by 
family No. i, only one half as much and cheaper cuts 
as boiling pieces, stew, rump roast, etc., were used by 
family No. 2 ; 5 pounds of beans and 5 pounds of cheese 
taking the place of some of the meat. Family No. i 
consumed 4 pounds of high-priced cereal breakfast foods, 
supposing they contained a larger amount of nutrients 
than were actually present. In place of the 4 pounds 
of high-priced cereal breakfast foods of family No. i, 
family No. 2 used 5 pounds of oatmeal purchased in 
bulk. Family No. i bought their cake and pastry for 
^3.00, while those of family No. 2 were home made and 
cost ;^ 1. 00. Family No. 2 used 2 pounds less butter per 
week because of the preparation and use of home-made 
shortening from beef suet and milk. They also pur- 
chased a smaller amount of tea, coffee, and spices than 
family No. i. Family No. 2 consumed a larger quantity 
of less expensive fruits and vegetables than family No. i, 
who ate 75 cents' worth of mushrooms with the idea that 
they contained as much protein as meat, but analyses 
show that mushrooms contain no more nutrients than 
potatoes and similar vegetables. In place of the celery 
and oranges, apples and prunes were used by family 
No. 2. The same amount of potatoes was used by each. 
Fifty cents was spent for milk by family No. i and 



DIETARY STUDIES 



257 



^i.oo by family No. 2. The total amount expended for 
food by family No. i was $23.45, while family No. 2 
purchased a greater variety of foods for $11.30, as well 
as foods containing more nutrients. The approximate 
amounts of nutrients in the foods purchased by the two 
families are given in the following table, from which it 
will be observed that family No. 2 obtained a much 
larger amount of total nutrients and was better fed at 
considerably less expense than family No. i. 

Nutrients in Foods Consumed. — Family No. i 





Protein 
Lb. 


Fat 
Lb. 


Carbohydrates 
Lb. 


20 lb. bread 

10 lb. loin steak 

20 lb. rib roast 

4 lb. cereals 

8 lb. butter 

25 lb. potatoes 

20 lb. milk 


1.98 

1.59 

2.68 

0.42 

0.04 • 

0.45 

0.70 


0.28 
1.76 
4.26 
0.06 
6.80 
003 
0.80 


11.42 

2.75 

3-^3 

I. GO 




7.86 


1399 


19.00 



258 HUMAN FOODS AND THEIR NUTRITIVE VALUE 
Family No. 2 





Protein 
Lb. 


Fat 
Lb. 


Carbohydrates 
Lb. 


15 lb. flour ....... 

5 lb. skim milk 

10 lb. round steak .... 
ID lb. beef 

5 lb. cheese 

5 lb. oatmeal 

6 lb. butter 

3 lb. shortening 

3 lb. prunes 

25 lb. apples 

25 lb. potatoes 

40 lb. milk 

5 lb. beans 


1.89 
0.16 
I.81 
1.32 
1.40 
0.78 
0.03 

0.03 
0.12 
0.45 
1.44 
1. 12 


0.12 
O.OI 

1.26 

2.02 

0.36 
5.10 
2.55 

0.03 
1.60 


II. 15 

0.26 

0.60 
2.50 

3-83 
1.90 
.3.00 




10.55 


14.80 


26.64 


Difference in nutrients in favor 
of family No. 2, consuming the 
cheaper combination of foods 


2.69 


0.81 


7.64 



255. Food in its Relation to Mental and Physical 
Vigor. — When the body is not properly suppHed with 
food, the best results in the form of productive work 
cannot be secured. There is a close relationship 
between the nature of the food consumed and mental 
activity, also ability to satisfactorily perform physical 
labor. " The productive power of the individual as 
well as of the nation depends doubtless upon many 
factors other than food, such as race, climate, habit, etc., 



DIETARY STUDIES 259 

but there is no gainsaying the fact that diet has also a 
profound and direct influence upon it."^^ 

If the body is diseased, it cannot make the right 
uses of the food, and often the food is blamed when 
the trouble is due primarily to other causes. The 
fact that a diseased digestive tract is unable to utilize 
some foods is no valid reason why these foods should 
be discarded in the dietary of persons in normal health, 
particularly when the food is in no way responsible for 
the disease. 

Some diseases are most prevalent in the case of a 
restricted diet, A change in the dietary of the Japa- 
nese navy greatly improved the health of the sailors. 

" The prevalence of kakke or beriberi in the navy turned the atten- 
tion of many medical specialists toward the problem of nutrition. . . . 
It was generally believed that there was some very close connection 
between the disease and the rice diet. . . . One outcome of these 
investigations was the passage of the food supply act of the navy 
in 1884. The ration provided in accordance with this act was 
sufficient to furnish an abundance of protein and energy. . . . Fol- 
lowing the change of ration in 1884, the prevalence of the disease 
was very materially diminished, and at the end of three years 
cases of kakke were practically unknown among the marines.'^ ^^ 

256. Dietary Studies in Public Institutions. — Dietary 
studies in public institutions, as prisons, and asylums 
for the insane, show that it is possible to secure greater 
variety of food containing a larger amount of nutrients, 
and even at a reduction in cost.^^ In such institutions 
it is important that the food should be not only ample 



26o HUMAN FOODS AND THEIR NUTRITIVE VALUE 

in amount, but wholesome and nutritious, as many of 
the inmates respond both physically and mentally to 
an improved diet. For humanitarian as well as eco- 
nomic reasons institutional dietetics should more gener- 
ally be placed under the supervision of skilled dietists. 



CHAPTER XVIII 
RATIONAL FEEDING OF MAN 

257. Object. — Rational feeding of man has for its 
object the regulation of the food supply in accord with 
the demands of the body. It is based upon the same 
principles as the rational feeding of animals ; in each, 
the best results in the way of health, amount of labor 
performed, and economy are secured when the body 
receives nutrients sufficient for the production of heat 
and energy and for the repair of worn-out tissues. Ra- 
tional feeding is simply regulation of the food, both 
as to kind and amount, to meet the needs of the body.''^ 

258. Standard Rations. — In human feeding, as in 
animal feeding, it is not possible to lay down hard and 
fast rules as to the quantity of nutrients required for 
a standard ration.^^ As stated in the chapter on Die- 
tary Studies, such standards have been proposed, but 
they are to be considered as tentative rather than abso- 
lute, for the amount of food required by different persons 
must necessarily vary with the individuality. While 
it is impossible to estabhsh absolute standards, any 
large variation from the provisional standards usually 

261 



262 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

results in lessened ability to accomplish work, ill health, 
or increased expense. 

259. Amounts of Food Consumed. — The approximate 
amounts of some food articles consumed per day are 
as follows : 





Range 


Approximate 
Amount in Lbs. 


Bread 


6 to 14 OZ. 
2 to 5 OZ. 

8 to 16 oz. 
I to 4 oz. 

1 to 4 oz. 
8 to 32 oz. 

2 to 5 oz. 
4 to 12 oz. 
I to 4 oz. 


0.50 
0.12 
0.75 
0.12 
0.12 


Butter 

Potatoes 


Cheese 

Beans 

Milk 


Suo'ar 


20 


Meats 

Oatmeal 


0.25 
0.12 



In the calculation of rations it is desirable that the 
amount of any food article should not exceed that des- 
ignated, unless for some special reason it has been 
found the food can consistently be increased. The 
amount of nutrients given in dietary standards is for 
one day, and the nutrients may be divided among the 
three meals as desired. It is to be noted that, or- 
dinarily, the foods which supply carbohydrates are 
flour, corn meal, cereal products, potatoes, beans, sugar, 
and milk ; those which supply fat are milk, butter, 
lard, and meats; and those which supply protein in 



RATIONAL FEEDING OF MAN 263 

liberal amounts are beans, cheese, meats, oatmeal, cereals, 
bread, and milk. 

260. Average Composition of Foods. — The amounts 
of nutrients in foods are determined from the average 
composition of the foods. These figures for average 
composition are based upon analyses of a large number 
of samples of food materials." In individual cases it 
will be found that foods may vary from the standards 
given; as for example, milk may contain from 2.5 to 5 
per cent of fat, while the protein and fat of meats vary 
appreciably from the figures given for average compo- 
sition. With the cereals and vegetable foods, variations 
from the standards are small. In the table, the com- 
position of the food as purchased represents all of the 
nutrients in the food, including those in the refuse, 
trimmings, or waste, while the figures for the edible por- 
tion represent the nutrients in the food after deducting 
what is lost as refuse. In making calculations, the 
student should use the figures given for the foods as 
purchased, unless the weights are of the edible portion 
only. The figures in the table are on the basis of per- 
centage amounts, or nutrients in 100 pounds of food. 
By moving the decimal point two places to the left, the 
figures will represent the nutrients in one pound, and 
if this is multipUed by the number of pounds or fraction 
of a pound used, the quantity of nutrients is secured. 
For example, suppose bread contains 9.5 per cent of 
protein and 56 per cent of carbohydrates, i pound 



264 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

would contain 0.095 pound of protein, 0.56 pound of 
carbohydrates; and 0.5 of a pound would contain 
approximately 0.05 pound of protein and 0.28 pound 
of carbohydrates. In calculating rations, it is not 
necessary to carry the figures to the third decimal 
place. 




Fig. 60.— Food Articles for a Human Ration. 



261. Example of a Ration. — Suppose it is desired to 
calculate a ration for a man at light muscular work. 
First, note the requirements in the way of nutrients in 
the table " Dietary Standards," Section 246. Such a 
ration should supply approximately 0.22 pound each of 
protein and fat, and 0.77 pound of carbohydrates, and 
should yield 2800 calories. A trial ration is made by 
combining the following : 



RATIONAL FEEDING OF MAN 



265 



Bread 
Butter 
Potatoes 
Milk . 
Sugar 
Beef . 
Ham . 
Oatmeal 
Eggs . 



Pound 
0.50 
0.12 
0.75 
1.00 
0.12 
0.25 
0.20 
0.12 
0.25 



The quantities of nutrients in these food materials are 

approximately as follows : 

Ration for Man at Moderate Work 





Lb. 


Protein 
Lb. 


Fat 
Lb. 


C.H. 
Lb. 


Calories 


Bread 


o.tro 


0.05 

O.OI 
0.04 

0.05 
0.03 
0.02 
0.03 


o.oi 
o.io 

0.04 

0.03 
0.07 

o.oi 

0.03 


0.29 

0.12 
0.05 
0.12 

0.08 
0.01 


653 
432 
244 

323 
192 
218 

331 

223 
164 

25 


Butter 


0.50 
0.12 


Potato 

Milk 


0.75 
I 00 


Sugar 

Beef (round) .... 

Ham 

Oatmeal 

Eggs 

Squash 


0.12 
0.25 
0.20 
0.12 
0.25 
0.20 






0.23 


0.29 


0.67 


2805 



It is to be noted that this ration contains approxi- 
mately the amoimt of protein called for in the standard 



266 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

ration, while the fat is slightly more and the carbohy- 
drates are less. The food value of the ration is prac- 
tically that called for in the standard. This ration is 
sufficiently near the standard to supply the nutrient 
requirements of a man at light muscular work. To 
supply palatability, some fruit and vegetables should 
be added to the ration. These will contribute but Httle 
to the nutrient content, but are necessary in order to 
secure health and the best returns from the other foods, 
and as previously stated, they are not to be estimated 
entirely upon the basis of nutrient content. A number 
of food articles could be substituted in this ration, if 
desired, either in the interests of economy, palatability, 
or personal preference. 

262. Requisites of a Balanced Ration. — Reasonable 
combinations of foods should be made to form balanced 
rations.^ A number of foods slow of digestion, or which 
require a large amount of intestinal work, should 
not be combined ; neither should foods which are 
easily digested and which leave but little indigestible 
residue. After a ration has been calculated and found 
to contain the requisite amount of nutrients, it should be 
critically examined to see whether or not it fulfills the 
following requirements : 

1 . Economy and adaptability to the work required. 

2. Necessary bulk or volume. 

3. Desired physiological influence of the foods upon the digestive 

tract, whether constipating or laxative in character. 

4. Ease of digestion. 



RATIONAL FEEDING OF MAN 267 

5. Effect upon health. It is recognized that there are foods 
wholesome and nutritious, that cannot be used by some per- 
sons, while with others the same foods can be consumed 
with impunity. 

As explained in the chapter on Dietary Studies, the 
nutrients should be supplied from a number of foods 
rather than from a few, because it is believed the various 
nutrients, particularly the proteins, are not absolutely 
identical from all sources, or equal in nutritive value. 

EXAMPLES 

1. Calculate a ration for a man with little physical exercise. 

2. Calculate a ration for a man at hard muscular labor, and give 

the approximate cost of the ration. 

3. Calculate the amounts of food and the nutrient requirements 

for a family of seven for 10 'days ; five of the family to con- 
sume 0.8 as much as an adult. Calculate the cost of the 
food ; then calculate on the same basis the probable cost of 
food for one year, adding 20 per cent for fluctuation in 
market price and additional foods not included in the list. 

4. Weigh out the food articles used in problem No. 2, and appor- 

tion them among three meals. 



CHAPTER XIX 

WATER 

263. Importance. — Water is one of the most essential 
food materials. It enters into the composition of the 
body, and without it the nutrients of foods would be 
unavailable, and life could not be sustained. Water 
unites chemically with various elements to form plant 
tissue and supplies hydrogen and oxygen for the produc- 
tion of organic compounds within the leaves of plants. 
In the animal economy it is not definitely known 
whether or not water furnishes any of the elements of 
which the tissues are composed, as the food contains 
liberal amounts of hydrogen and oxygen ; it is necessary 
mainly as the vehicle for distributing nutrients in sus- 
pension and solution, and as a medium in which chemical, 
physical, and physiological changes essential to life 
processes take place. From a sanitary point of view, 
the condition of the water supply is of great importance, 
as impure water seriously affects the health of the con- 



264. Impurities in Water. — Waters are impure be- 
cause of: (i) excessive amounts of alkaline salts and 
other mineral compounds ; (2) decaying animal and 

268 



WATER 



269 



vegetable matters which act chemically as poisons and 
irritants, and which may serve as food for the develop- 
ment of objectionable bacterial bodies; and (3) injurious 




Fig. 61. — Dirt and Impurities in a Surface Well Water. 



bacteria. The most common forms of impurities are 
excess of organic matter and bacterial contamination. 
The sanitary condition of water is greatly influenced by 
the character of the soil through which it flows and the 
extent to. which it has been polluted by surface drain- 



age 



88 



270 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

265. Mineral Impurities. — The mineral impurities of 
water are mainly soluble alkaline and similar compounds 
dissolved by the water in passing through various layers 
of soil and rock. When water contains a large amount 
of sodium chloride, sodium sulphate or carbonate, or 
other alkaline salts, it is termed an " alkali water." 
Where water passes through soil that has been largely 
formed from the decay of rocks containing alkaline 
minerals, the water dissolves some of these minerals and 
becomes alkaline. The kind of alkali determines the 
character of the water ; in some cases it is sodium car- 
bonate, which is particularly objectionable. The con- 
tinued use of strong alkali water causes digestion dis- 
orders, because of the irritating action upon the digestive 
tract. Hard waters are due to the presence of lime 
compounds. In regions where limestone predominates, 
the carbon dioxid in water acts as a solvent, producing 
hard waters. Waters that are hard on account of the 
presence of calcium carbonate give a deposit when 
boiled, due to hberation of the carbon dioxid which is 
the material that renders the lime soluble. Calcium 
sulphate, or gypsum, on the other hand, imparts per- 
manent hardness. There is no deposit when such 
waters are boiled. A large number of minerals are 
found in various waters, often sufficient in amount to 
impart physiological properties. Water that is highly 
charged with mineral matter is difficult to improve 
sufficiently for household purposes. About the only 
way is by distillation.^^ 



WATER 271 

266. Organic Impurities. — Water that flows over the 
surface of the ground comes in contact with animal and 
vegetable material in various stages of decay, and as a 
result some is dissolved and some is mechanically carried 
along by the water. After becoming soluble, the organic 
matter undergoes further chemical changes, as oxidation 
and nitrification caused by bacteria. If the organic 
matter contain a large amount of nitrogenous material, 
particularly of proteid origin, a series of chemical 
changes induced by bacterial action takes place, resulting 
in the production of nitrites. The nitrifying organisms 
first produce nitrous acid products (nitrites), and in the 
further development of the nitrifying process these are 
changed to nitrates. The ammonia formed as the result 
of the decomposition of nitrogenous organic matter readily 
undergoes nitrification changes. Nitrates and nitrites 
alone are not injurious in water, but they are usually 
associated with objectionable bacteria and generally 
indicate previous contamination.^^ 

267. Interpretation of a Water Analysis. — '' Total 
soHd matter" represents all the mineral, vegetable, and 
animal matter which a water contains. It is the residue 
obtained by evaporating the water to dryness at a tem- 
perature of 212° F. Average drinking water contains 
from 20 to 90 grains per gallon of soHd matter. " Free 
ammonia" is that formed as a result of the decomposi- 
tion of animal or vegetable matter containing nitrogen. 
Water of high purity usually contains less than 0.07 



272 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

parts per million of free ammonia. ** Albuminoid am- 
monia " is derived from the partially decomposed ani- 
mal or vegetable material in water. The greater the 
amount of nitrogenous organic impurities, the higher 
the albuminoid ammonia. A good drinking water ought 
not to contain more than o.io part per million of albu- 
minoid ammonia. An abnormal quantity of chlorine 
indicates surface drainage or sewage contamination, or 
an excess of alkaUne matter, as common salt. Nitrites 
should not be present, as they are generally associated 
with matter not completely oxidized. Nitrites are usu- 
ally considered more objectionable than nitrates; both 
are innocuous unless associated with disease-producing 
nitroorganisms. 

268. Natural Purification of Water. — River waters 
are sometimes dark colored because of large amounts of 
dissolved organic matter, but in contact with the sun 
and air they gradually undergo natural purification and 
the organic matter is oxidized. However, absolute reli- 
ance cannot be placed upon natural purification of a 
bad water, as the objectionable organisms often have 
great resistive power. There is no perfectly pure water 
except that prepared in the chemical laboratory by dis- 
tillation. All natural waters come in contact with the 
soil and air, and necessarily contain impurities propor- 
tional to the extent of their contamination. 

269. Water in Relation to Health. — There are many 
diseases, of which typhoid fever is a type, that are dis- 



WATER 273 

tinctly water-born. The typhoid bacilli, present in count- 
less numbers in the feces of persons suffering or con- 
valescent from typhoid fever, find their way into streams, 
lakes, and wells. ^^ They retain their vitality, and when 
they enter the digestive tract of an individual, rapidly 
increase in numbers. Numerous disastrous outbreaks 
of typhoid fever have been traced to contamination of 
water. Coupled with the sanitary improvement of a 
city's water supply, there is diminution of typhoid fever 
cases, and a noticeable lowering of the death rate. 
Many cities and villages are dependent for their water 
upon rivers and lakes into which surface drainage finds 
its way, with all contaminating substances. Mechanical 
sedimentation and filtration greatly improve waters of 
this class, but do not necessarily render them entirely 
pure. Compounds of iron and aluminium are sometimes 
added in small amounts, under chemical supervision, 
to such waters to precipitate the organic impurities. 
Spring waters are not entirely above suspicion, as often- 
times the soil through which they flow is highly polluted. 
All water of doubtful purity should be boiled, and there 
are but few natural waters of undoubted purity. There 
is no such thing as absolutely pure water in a state of 
nature. The mountain streams perhaps approach near- 
est to it where there are no humans to pollute the banks ; 
but then there are always the beasts and birds, and they, 
too, are subject to disease. There are very few waters 
that at some time of the year and under some conditions 
are not contaminated with disease-producing organisms. 

T 



2 74 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

No matter how carefully guarded are the banks of lakes 
furnishmg the water supply of cities, more or less ob- 
jectionable matter will get in. In seasons of heavy rains, 
large amounts of surface water enter the lakes, carrying 
along the filth gathered from many acres of land drained 
by the streams entering the lakes. Some of the most 
serious outbreaks of typhoid fever have come from 
temporary contamination of ordinarily fairly good drink- 
ing water. In general, too little attention is given to the 
purity of drinking water. It is just as important that 
water should be boiled as that food should be cooked. 
One of the objects of cooking is to destroy the injurious 
bacteria, and they are frequently more numerous in the 
drinking water than in the food. 

The argument is sometimes advanced that the min- 
eral matter present in water is needed for the construc- 
tion of the bone and other tissues of the body, and that 
distilled water fails to supply the necessary mineral 
matter. This is an erroneous assumption, as the min- 
eral matter in the food is more than sufficient for this 
purpose. When water is highly charged with mineral 
salts, additional work for their elimination is called for 
on the part of the organs of excretion, particularly the 
kidneys; and furthermore, water nearly saturated with 
minerals cannot exert its full solvent action. 

In discussing the immediate benefits resulting from 
improvement of water, Fuertes says : ^^ 

"Immediately after the change to the ' four mile intake ' at Chi- 
cago in 1893, there was a great reduction in typhoid. Lawrence, 



WATER 275 

Mass., showed a great improvement with the setting of the fihers in 
operation in September, 1893 ; fully half of the deaths in 1894 were 
among persons known to have used the unfiltered canal water. 
The conclusion is warranted that for the efficient control of the 
death rate from typhoid fever it is necessary to have efficient sewer- 
age and drainage, proper methods of living, and pure water. The 
reason why our large cities, wdiich are all provided with sewerage, 
have such high death rates is therefore without doubt their continu- 
ance of the filthy practice of supplying drinking water which carries 
in solution and suspension the washings from farms, from the 
streets, from privies, from pigpens, and the sewage of cities. . . . 
And also we should recognize the importance of flies and other 
winged insects and birds which feed on ofifal as carriers of bacteria 
of specific diseases from points of infection to the watersheds, and 
the consequent washing of newly infected matter into our drinking 
water by rains." 

There is a very close relationship between the sur- 
face water and that of shallow wells. A shallow well 
is simply a reservoir for surface water accumulations. 
It is stated that, when an improved system of drainage 
was introduced into a part of London, many of the 
shallow wells became dry, indicating the source from 
which they received their supply. Direct subterranean 
connection between cesspools and wells is often traced 
in the following way : A small amount of lithium, 
which gives a distinct flame reaction, and a minute trace 
of which can be detected with the spectroscope, is 
placed in the cesspool, and after a short time a lithium 
reaction is secured from the well water. 

Rain water is relied upon in some localities for drink- 
ing purposes. That collected in cities and in the vicin- 



276 HUMAN FOODS AND THEiR NUTRITIVE VALUE 

ity of barns and dwellings contains appreciable amounts 
of organic impurities. The brown color is due to the 
impurities, ammonium carbonate being one of these. 
There are also traces of nitrates and nitrites obtained 
from the air. When used for drinking, rain water 
should be boiled. 

270. Improvement of Waters. — Waters are improved 
by: (i) boiling, which destroys the disease-producing 
organisms; (2) filtration, which removes the materials 
mechanically suspended in the water ; and (3) distilla- 
tion, which eliminates the impurities in suspension and 
solution, as well as destroys all germ life. 

271. Boiling Water. — In order to destroy the bac- 
teria that may be in drinking water, it is not sufficient 
to heat the water or merely let it come to a boil. It 
has been found that if water is only partially sterilized 
and then cooled in the open air, the bacteria develop 
more rapidly than if the water had not been heated at 
all. It should boil vigorously five to ten minutes ; 
cholera and typhoid bacteria succumb in five minutes 
or less. Care should be taken in cooling that the water 
is not exposed to dust particles from the air nor placed 
in open vessels in a dirty refrigerator. It should be 
kept in perfectly clean, tight-stoppered bottles. These 
bottles should be frequently scalded. Great reliance 
may be placed upon this method of water purification 
when properly carried out. 



WATER 



277 



272. Filtration. — Among the most efficient forms of 
water filters are the Berkefeld and Pasteur. The Pas- 
teur filter is made of unglazed 
porcelain, and the Berkefeld 
of fine infusorial earth (finely 
divided Si02). Both are por- 
ous^ and allow a moderately 
rapid flow of water. The 
flow from the Berkefeld fil- 
ter is more rapid than from 
the Pasteur. The mechani- 
cal impurities of the water 
are deposited upon the filter- 
ing surface, due to the attrac- 
tion which the material has 
for particles in suspension. 
These particles usually are 
the sources of contamination 
and carry bacteria. When 
first used, filters are satisfac- 
tory, but unless carefully 
looked after they soon lose 
their abiHty to remove germs from the water and may 
increase the impurity by accumulation. Small faucet 
filters are made of porous stone, asbestos, charcoal, etc. 
Many of them are of no value whatever or are even worse 
than valueless. Filters should be frequently cleansed in 
boiling water or in steam under pressure. Unless this 
is done, the filters may become incubators for bacteria. 




Fig. 62. 



- Pasteur Water 
Filters. 



278 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

273. Distillation. — When an unquestionably pure 
water supply is desired, distillation should be resorted 
to. There are many forms of stills for domestic use 
which are easily manipulated and produce distilled 
water economically.^^ The mineral matter of water is 



1^VI 


■■■ 


1 




■~";a» 


/- . \ 


V 




IHBBBiiflllH 


■■■^■^■■i 


II 



Fig. 63.— Water Still. 

in no way essential for any functional purpose, and 
hence its removal through distillation is not detrimental. 

274. Chemical Purification. — Purification of water by 
the use of chemicals should not be attempted in the 
household or by inexperienced persons. When done 
under supervision of a chemist or bacteriologist, it may 
be of great value to a community. Turneaure and 



WATER 



279 



Russell,^'* in discussing the purification of water by 
addition of chemicals, state : 

" There are a considerable number of chemical substances that may 
be added to water in order to purify it by carrying down the sus- 
pended matter as well as bacteria, by sedimentation. Such a pro- 
cess of purification is to be seen in the addition of alum, sulphate of 
iron, and calcium hydrate to water. Methods of this character are 
directly dependent upon the flocculating action of the chemical 
added, and the removal of the bacteria is accomplished by subsid- 



275. Ice. — The purity of the ice supply is also of 
much importance. While freezing reduces the number 
of organisms and lessens their vitality, it does not make 
an impure water absolutely wholesome. The way, too, 
in which ice is often handled and stored subjects it to 
contamination, and foods which are placed in direct 
contact with it mechanically absorb the impurities which 
it contains. For cooling water, ice should be placed 
around rather than in it. Diseases have frequently 
been traced to impure ice. The only absolutely pure 
ice is that made from distilled water. 

276. Mineral Waters. — When water is charged with 
carbonic acid gas under pressure, carbonated water re- 
sults, and when minerals, as salts of sodium, potassium, 
or lithium, are added, artificial mineral waters are pro- 
duced. Natural mineral waters are placed on the 
market to some extent, but most mineral waters are 
artificial products and they are sometimes prepared 
from water of low sanitary character. Mineral waters 



28o HUMAN FOODS AND THEIR NUTRITIVE VALUE 

should not be used extensively except under medical 
direction, as many have pronounced medicinal proper- 
ties. Some of the constituents are bicarbonates of so- 
dium, potassium, and lithium ; sulphates of magnesium 
(Epsom salts) and calcium; and chloride of sodium. 
The sweetened mineral waters, as lemonade, orangeade, 
ginger ale, and beer, contain sugar and organic acids, as 
citric and tartaric, and are flavored with natural or arti- 
ficial products. Most of them are prepared without 
either fruit or ginger. Natural mineral waters used 
under the direction of a physician are often beneficial 
in cases of chronic digestion disorders or other diseases. 

277. Materials for Softening Water. — The materials 
most commonly used for softening water are sodium 
carbonate (washing soda), borax, ammonia, ammonium 
carbonate, potash, and soda lye. Waters that are very 
hard with limestone should have a small amount of 
washing soda added to them. Two ounces for a large 
tub of water is the most that should be used, and it 
should first be dissolved in a Httle water. If too much 
soda is used, it is injurious, as only a certain amount can 
be utilized for softening the water, and the excess simply 
injures the hands and fabric. When hard limewater is 
boiled and a very little soda lye added, a precipitate of 
carbonate of lime is formed, and then if the water is 
strained, it is greatly improved for washing purposes. 
Borax is valuable for making some hard waters soft. 
It is not as strong in its action as is sodium carbonate. 



WATER 281 

For the hardest water ^ pound of borax to a large tub- 
ful may be used ; most waters, however, do not need so 
much. Ammonia is one of the most useful reagents 
for softening water. It is better than washing soda 
and borax, because the ammonia is volatile and does 
not leave any residue to act on the clothes, thus causing 
injury. For bathing purposes, the water should be 
softened with ammonia, in preference to any other 
material. Ammonia should not be poured directly into 
hot water ; it should be added to the water while cold, 
or to a small quantity of cold water, and then to the 
warm water, as this prevents the ammonia from vapor- 
izing too readily. Ammonia produces the same effect 
as potash or soda lye, without leaving a residue in the 
garments washed. It is especially valuable in washing 
woolen goods or materials liable to shrink. Waters 
which are hard with alum salts are greatly benefited by 
the addition of ammonia. A little in such a water will 
cause a precipitate to form, and when the water is 
strained it is in good condition for cleaning purposes. 
Ammonium carbonate is used to some extent as a soft- 
ening and cleaning agent, and is valuable, as there is no 
injurious effect upon clothing, because it readily volatil- 
izes. Caustic potash and caustic soda are sometimes 
employed for softening water, but they are very active 
and are not adapted to washing colored or delicate 
fabrics. They may be used for very heavy and coarse 
articles that are greasy, — not more than a gram in a 
gallon of water. Bleaching powder is not generally a 



282 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

safe material for cleansing purposes, as it weakens the 
texture of clothing. After a contagious disease, articles 
may be soaked in water containing a little bleaching 
powder and a few drops of carbolic acid, followed by- 
thorough rinsing and bleaching in the sun. But as a 
rule formaHne is preferable for disinfecting clothing. 
It can be used at the rate of about one pound to 100 
gallons of water. Bleaching powder, caustic potash 
or soda, and strong soap are not suitable for cleaning 
woodwork, because of the action of the alkali on paint 
and wood ; they roughen the surface and discolor the 
paint. Waters vary so in composition, that a material 
suitable for softening one may not prove to be the best 
for softening another. The special kind must be de- 
termined largely by trial, and it should be the aim to 
use as little as possible. When carbolic acid, formaline, 
bleaching powder, and caustic soda are used, the hands 

should be protected and the clothes 

should be well rinsed. 

278. Economic Value of a Pure 

Water Supply. — From a financial 

point of view, the money spent in 

securing pure water is one of the 

Fig. 64. — Typhoid best investments a community can 

make. Statisticians estimate the 

death of an adult results in a loss to the state of from 

;^iooo to $5000; and to the losses sustained by death 

must be added those incurred by sickness and by less- 




WATER 283 

ened quality and quantity of work through impaired 
vitaUty, — all caused by using poor drinking water. 
Wherever plants have been installed for improving the 
sanitary condition of the water supply, the death rate 
has been lowered and the returns to the community 
have been far greater than the cost of the plant. Im- 
pure water is the most expensive food that can be 
consumed. 



CHAPTER XX 

FOOD AS AFFECTED BY HOUSEHOLD SANITATION 
AND STORAGE 

279. Injurious Compounds in Foods. — An ordinary 
chemical analysis of a food determines only the nutri- 
ents, as protein, carbohydrates, and fats ; and unless 
there is reason to believe the food contains injurious 
substances no special tests for these are made. There 
are a number of poisonous compounds that foods may 
contain, and many of them can but imperfectly be 
determined by chemical analysis. Numerous organic 
compounds are produced in foods as the result of the 
workings of microorganisms ; some of these are poison- 
ous, while others impart only special characteristics, 
as taste and odor. The poisonous bacteria finding their 
way into food produce organic compounds of a toxic 
character ; and hence it is that the sanitary condition 
of a food, as influenced by preparation and storage, is 
often of more vital importance than the nutrient 
content. ^^ 

280. Sources of Contamination of Food. — As a rule, 
too little attention is given to the sanitary handUng and 
preparation of foods. They are often exposed to impure 

284 



FOOD AS AFFECTED BY SANFfATlON AND STORAGE 285 

air and to the dust and filth from unclean streets and 
surroundings, and as a result they become inoculated 
with bacteria, which are often the disease-producing 
kind. Gelatine plates exposed by bacteriologists under 
the same conditions as foods develop large numbers of 




Fig. 65. —Tuberculosis Bacilli. (After Conn.) 
Often present in dust particles and contaminated foods. 

injurious microorganisms. In order to avoid contami- 
nation in the handling of food, there must be: (i) pro- 
tection from impure air and dust; (2) storage in clean, 
sanitary, and ventilated storerooms and warehouses; 
(3) storage of perishable foods at a low temperature so 
as to retard fermentation changes ; and (4) workmen free 
from contagious diseases in all occupations pertaining 



286 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

to the preparation of foods. Ordinarily, foods should 
not be stored in the paper wrappers in which they 
are purchased, as unclean paper is often a source of 
contamination. 

281. Sanitary Inspection of Food. — During recent 
years some state and city boards of health have in- 
troduced sanitary inspection of foods, with a view 
of preventing contamination during manufacture and 
transportation, and this has done much to improve 
the quality and wholesomeness. Putrid meats, fish, and 
vegetables are not allowed to be sold, and foods are 
required to be handled and stored in a sanitary way. 
Next to a pure water supply, there is no factor that so 
greatly influences for good the health of a community 
as the sanitary condition of the food. While the cook- 
ing of foods destroys many organisms, it often fails to 
render innocuous the poisons which they produce, and 
furthermore the unsound foods when cooked are not en- 
tirely wholesome, and they have poor keeping qualities. 

Often meats, vegetables, and other foods eaten un- 
cooked, as well as the numerous cooked foods, are 
exposed in dirty market places, and accumulate large 
amounts of filth, and are inoculated with disease germs 
by flies. Protection of food from flies is a matter of 
vital importance, as they are carriers of many diseases. 
In the case of typhoid fever, next to impure drinking 
water flies are credited with being the greatest dis- 
tributors of the disease germs.^ 



FOOD AS AFFECTED BY SANITATION AND STORAGE 287 

282. Infection from Impure Air. — The dust particles 
of the air contain decayed animal and vegetable matter 
in which bacteria are present ; these find their way into 
the food when it is not carefully protected, into the 
water supply, and also into the lungs and other organs 




Fig. 66. — Diphtheria Bacilli. (After Conn.) 
Often present in dust particles and in food unprotected from dust, 

of the body. When foods are protected from the me- 
chanical impurities which gain access through the air, 
and fermentation is delayed by storage at' a low tem- 
perature, digestion disorders are greatly lessened. From 
a sanitary point of view, the air of food storerooms and 
of living rooms should be of equally high purity. When 
foods are kept in unventilated living rooms, they become 



288 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

contaminated with the impurities thrown off from the 
hmgs in respiration, which inchide not only carbon di- 
oxid, but the more objectionable toxic organic materials. 
Vegetable foods need to be stored in well-ventilated 
places, as the plant cells are still alive and carrying on 
life functions, as the giving off of carbon dioxid, which 
is akin to animal respiration ; in fact, it is plant-cell 
respiration. Provision should be made for the removal 
of the carbon dioxid and other products, as they con- 
taminate the air. When vegetable tissue ceases to pro- 
duce carbon dioxid, death and decay set in, accompanied 
by fermentation changes. 

283. Storage of Food in Cellars. — Cellars are often 
in a very unsanitary condition, damp, poorly lighted, un- 
ventilated, and the air filled with floating particles from 
decaying vegetables. The walls and shelves absorb the 
dust and germs from the foul air and are bacterially con- 
taminated, and whenever a sound food is stored in such 
a cellar, it readily becomes inoculated with bacteria. 
There is a much closer relationship existing between the 
atmosphere of the cellar and that of the house than is 
generally realized. An unclean cellar means contami- 
nated air throughout the house. When careful attention 
is given to the sanitary condition of the cellar, many of 
the more common diseases are greatly reduced. Cases 
of rheumatism have often been traced to a damp cellar. 
In some localities where the cellars are unusually un- 
sanitary, there is in the season of spring rains, when 



FOOD AS AFFECTED BY SANITATION AND STORAGE 289 



they are especially damp and contain the maximum of 
decayed vegetation, a prevalence of what might be called 
"cellaritis." The symp- 
toms differ and the 
trouble is variously at- 
tributed, but the real 
cause is the same, al- 
though overlooked, for, 
unfortunately, doctors 
do not visit the cellar. 
Cellars should be 
frequently cleaned and 
disinfected, using for 
the purpose some of 
the well-known disin- 
fectants, as formaline, 
bleaching powder, or a 
dilute solution of car- 
bolic acid. It has been 
found in large cities, 
when the spread of 
such diseases as yellow 
fever was imminent, 
that a general and thorough cleaning up of streets and 
cellars with the improved sanitary conditions resulting 
greatly lowered the usual death rate. 




Fig. 67. — Dl'ng Functus. 

(After Butters.) 

Often present on surface of unclean 

vegetables. 



284. Sunlight, Pure Water, and Pure Air as Disin- 
fectants. — The most effectual and valuable disinfectants 
u 



290 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

are sunlight, pure water, and pure air. Many kinds of 
microorganisms, particularly those that are disease-pro- 
ducing, are destroyed when exposed for a time to sun- 
light. The chemical action of the sun's rays is destructive 
to the organic material which makes up the composition 
of many of these organisms, while higher forms of or- 
ganic life are stirred into activity by it. The disinfecting 
power of sunHght should be made use of to the fullest 
extent, not only in the house, but plenty of sunlight 
should also be planned for in constructing barns and 
other buildings where milk- and meat-producing animals 
are kept. Pure water is also a disinfectant, but when 
water becomes polluted it loses this power. Many dis- 
ease-producing organisms are rendered inactive when 
placed in pure water. Water contains more dissolved 
oxygen than air, and apparently a portion of the oxygen 
in water is in a more active condition than that in air. 
Pure air, too, is a disinfectant ; the ozone and hydrogen 
peroxide and oxides of nitrogen, which are presejnt in 
traces, exert a beneficial influence in oxidizing organic 
matter. Fresh air and sunHght, acting jointly, are na- 
ture's most effectual disinfectants. Sunshine, fresh air, 
and pure water are a health-producing trinity. In dis- 
cussing the importance of pure air, water, and sunlight, 
Ellen H. Richards^'' says : 

" The country dweller surrounds his house with evergreens or shade 
trees, the city dweller is surrounded with high brick walls. Blinds, 
shades, or thick draperies shut out still more, and prevent the bene- 
ficial sunlight from acting its role of germ prevention and germ 



FOOD AS AFFECTED BY SANITATION AND STORAGE 29I 

destruction. Bright-colored carpets and pale-faced children are the 
opposite results which follow. Sunlight, pure air, and pure water are 
our common birthright which we often bargain away for so-called 
comforts." 

And Dr. Woods Hutchinson says of sunlight : 

" It is a splendid and matchless servant in the promoting of 
healthfulness of the house, for which no substitute has yet been dis- 
covered. It is the foe alike of bacilli and the blues ; the best tonic 
ever yet invented for the liver and for the scalp, and for everything 
between, the only real complexion restorer, and the deadliest foe of 
dirt and disease." 



285. Utensils for Storage of Food. — In order that 
dishes and household utensils may be kept in the 
best sanitary condition, they should be free from seams, 
cracks, and crevices where 
dust and dirt particles can 
find lodgment. From the 
seams of a milk pail that 
has not been well washed, 
decaying milk solids can 
be removed with the aid 
of a pin or a toothpick. 
This material acts as a 
'' starter " or culture when 
pure, fresh milk is placed 
in the pail, contaminating 
it and causing it to become 
sour. Not only is this true of milk, but also of other 
foods. Wooden utensils are not satisfactory for the 




Fig. 68. — dirt and manure em- 
bedded IN Surface of Celery. 



292 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

handling, storage, or preparation of foods, as it is diffi- 
cult to keep wood in a sanitary condition. Uncleanliness 
of dishes in which foods are placed is too often caused 
by the use of foul dishcloths and failure to thoroughly 
wash and rinse the dishes. It is always well to rinse 
dishes with scalding water, as colds and skin diseases 
may be communicated from the edges of drinking glasses, 
and from forks and spoons, and, unless the dish towels 
are kept scrupulously clean, it is more sanitary to drain 
the dishes than to wipe them. 

286. Contamination from Unclean Dishcloths. -When 

the dishcloth is foul, the fat absorbed by the fibers be- 
comes rancid, the proteids undergo putrefaction changes 
with formation of ill-smelling gases containing nitrogen, 
the carbohydrates ferment and are particularly attractive 
to flies, and all the various disease germs collected on the 
surface of the dishcloth are, along with the rancid fat 
and other putrifying materials, distributed over the sur- 
face of the dishes with which the cloth comes in contact. 

287. Refrigeration. — At a low temperature the in- 
soluble or unorganized ferments become inactive, but 
the chemical ferments or enzymes are still capable of 
carrying on fermentation. Thus it is that a food, when 
placed in a refrigerator or in cold storage, continues to 
undergo chemical change. An example of such enzymic 
action is the curing of beef and cheese in cold storage. 
A small amount of ventilation is required when foods are 
refrigerated, just sufficient to keep up a slight circulation 



FOOD AS AFFECTED BY SANITATION AND STORAGE 



293 



of air. It seems not to be generally understood that all 
fermentation changes do not cease when food is placed 
in refrigerators, and this often leads to neglect in their 
care. CleanHness is equally as essential, or more so, in 
the refrigeration of food as in its handling in other ways. 




Fig. 69. — Contamination of Well Water from Surface Drainage. 
(After Farmers' Bulletin, U. S. Dept. Agr.) 

Too often the refrigerator is neglected, milk and other 
food is spilt, fining the cracks, and slow decomposition 
sets in. A well-cared-for refrigerator is an important 
factor in the preservation of food, but when it is neg- 
lected, it becomes a source of contamination. Unclean 
vegetables and food receptacles, impure ice and foul air, 
are the most common forms of contamination. The 



294 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

chemical changes which foods undergo during refriger- 
ation are such as result in softening of the tissues. 

288. Soil. — The soil about dwelUngs and places where 
foods are stored frequently becomes polluted with de- 
caying animal and vegetable matter, and in such soils 
disease-producing organisms readily find lodgment. 
Poorly drained soils containing an excess of vegetable 
matter furnish a medium in which the tapeworm and the 
germs of typhoid fever, lockjaw, and various diseases 
affecting the digestive tract, may propagate. The wind 
carries the dust particles from these contaminated 
places into unprotected food, where they cause fer- 
mentation changes and the disease germs multiply. 
In considering the sanitary condition of a locality, 
the character of the soil is an important factor. When- 
ever there is reason to suspect that a soil is unsanitary, 
it should be disinfected with hme or formaldehyde. Soils 
about dwellings need care and frequent disinfecting to 
keep them in a sanitary condition, equally as much as 
do the rooms in the dwellings.^^ In the growing of 
garden vegetables, frequently large quantities of ferti- 
lizers of unsanitary character are used, and vegetables 
often retain mechanically on their surfaces particles of 
these. To this dirt clinging to the vegetables have been 
traced diseases, as typhoid fever and various digestion 
disorders. 

289. Disposal of Kitchen Refuse. — Refuse, as vege- 
table parings, bones, and meat scraps, unless they are 



FOOD AS AFFECTED BY SANITATION AND STORAGE 295 

used for food for animals or collected as garbage, should 
preferably be burned ; then there is no danger of their 
furnishing propagating media for disease germs. Gar- 
bage cans should be kept clean, and well covered to 
protect the contents from flies. Where the refuse cannot 
be burned, it should be composted. For this, a well- 
drained place should be selected, and the refuse should 
be kept covered with earth to keep off the flies and 
absorb the odors that arise from the fermenting material, 
and to prevent its being carried away by the wind. 
Lime should be sprinkled about the compost heap, and 
from time to time it should be drawn away and the place 
covered with clean earth. It is very unsanitary to 
throw all of the kitchen refuse in the same place year 
after year without resorting to any means for keeping 
the soil in a sanitary condition. Although composting 
refuse is not as sanitary as burning, it is far more sani- 
tary than neglecting to care for it at all, as is too fre- 
quently the case. 

Ground polluted with kitchen refuse containing large 
amounts of fatty material and soap becomes diseased, so 
that the natural fermentation changes fail to take place, 
and the soil becomes *' sewage sick " and gets in such a 
condition that vegetation will not grow. Failure to 
properly dispose of kitchen refuse is frequently the cause 
of the spread of germ diseases, through the dust and 
flies that are attracted by the material and carry the 
germs from the refuse pile to food. 

Where there is no drainage system, disposal of the 



296 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

liquid refuse is a serious problem. Drain basins and 
cesspools are often resorted to, and these may become 
additional sources of contamination. As stated in the 
chapter on well water, direct communication is frequently 
established between such places and shallow wells. 



UBlllk 



-^11 



Fig. 70. — Plumbing of Sink. 

I, I, house side of trap, filled with water; 2, vent pipe; 3, drain pipe connect- 
ing with sewer. 



Where the only place for the disposal of waste water is 
the surface of the ground, it should be thrown some dis- 
tance from the house and where it will drain from and 
not toward the well. The land should be well drained 
and open to the sunlight. Coarse sand and lime should 
be sprinkled over it frequently, and occasionally the soil 
should be removed and replaced with fresh. Sunlight, 
aeration, and disinfection of the soil and good drainage 



FOOD AS AFFECTED BY SANITATION AND STORAGE 297 

are necessary, in order to keep in a sanitary condition 
the place where the dish water is thrown. 

Poor plumbing is often the cause of contaminated 
food. The gases which escape from unclean traps may 
carry with them solid particles of organic matter in 
various stages of decay. The "house side" of traps 
always ventilates into the rooms, and hence it is impor- 
tant that they be kept scrupulously clean. Where the 
drip pipe from the refrigerator drains directly into the 
sewerage system, there is always danger. Special atten- 
tion should be given to the care of plumbing near places 
where foods are stored. Frequently there are leaky 
joints due to settHng of the dwellings or to extreme 
changes in temperature, and the plumbing should be 
occasionally inspected by one familiar with the sub- 
ject.i^ 

290. General Considerations. — In order to keep food 
in the most wholesome condition, special care should be 
taken that all of its surroundings are sanitary. The air, 
the dishes in which the food is placed, the refrigerator, 
cellar or closet where stored, and the other food with 
which it comes in contact, all influence the wholesome- 
ness or cause contamination. A food may contain 
sufficient nutrients to give it high value, and yet, on 
account of products formed during fermentation, be 
poisonous. Foods are particularly susceptible to putre- 
faction changes, and chemicals and preservatives added 
as preventives, with a view of retarding these changes. 



298 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

are objectionable, besides failing to prevent all fermenta- 
tion from taking place. Intelligent thought should be 




Fig. 71. — A Petri Dish, showing Colonies of Bacteria produced 
BY allowing a House Fly to Crawl over Surface. 

(From Minnesota Experiment Station Bulletin No. 93.) 



exercised in the care of food, for the health of the con- 
sumer is largely dependent upon the purity and whole- 
someness of the food supply. 



CHAPTER XXI 
LABORATORY PRACTICE 

Object of Laboratory Practice, Laboratory Note-book, and Sugges- 
tions for Laboratory Practice. — The aim of the laboratory practice 
is to give the students an idea of the composition, uses, and values 
of food materials, and the part vv^hich chemistry takes in sanitation 
and household affairs ; also to enable them by simple tests to detect 
some of the more common adulterants in foods. 

Before performing an experiment, the student is advised to review 
those topics presented in the text which have a bearing upon the 
experiment, so that a clear conception may be gained of the relation- 
ship between the laboratory work and that of the class room. The 
student should endeavor to cultivate the power of observation and to 
grasp the principle involved in the work, rather than do it in a merely 
mechanical and perfunctory way. Neatness is one of the essentials for 
success in laboratory practice, and too much emphasis cannot be laid 
upon this requisite to good work. The student should learn to use his 
time in the laboratory profitably and economically. He should 
obtain a clear idea of what he is to do, and then do it to the best 
of his ability. If the experiment is not a success, repeat it. While 
the work is in progress it should be given undivided attention. Care 
should be exercised to prevent anything getting into the sinks that 
will clog the plumbing ; soil, matches, broken glass, and paper should 
be deposited in the waste jars. 

A careful record of the experiments should be kept by each student 
in a suitable note-book. It is suggested that those students desiring 
more time in writing out the experiments than the laboratory period 
affords, take notes as they make the various tests, and then amplify 
and rearrange them in the evening study time. The final writing up 
of the notes should, however, be done before the next laboratory 

299 



300 



HUMAN FOODS AND THEIR NUTRITIVE VALUE 



period. Careful attention should be given to the spelling, language, 
and punctuation, and the note-book should represent the student's 
individual work. He who attempts to cheat by copying the results 




Fig. 72. — Apparatus used in Laboratory Work. 
See page 301 for names, 

of others, only cheats himself. In recording the results of an experi- 
ment, the student should state briefly and clearly the following : 

1. Number and title of experiment. 

2. How the experiment is performed. 

3. What was observed. 

4. What the experiment proves. 



LABORATORY PRACTICE 



301 




Fig. 73.— Balance and Weights. 



List of Apparatus used in Experiments 



I Crucible Tongs 




I Test Tube Brush 


2 Evaporating Dishes 




I Burner and Tubing 


I Casserole 




2 Stirring Rods 


6 Beakers 




6 Watch Glasses 


12 Test Tubes 




2 Erlenmeyer Flasks 


I Wooden Stand 




I Package Filter Paper 


I Test Tube Stand 




I Box Matches 


I Sand Bath 




I Wire Gauze 


2 Funnels 




2 Burettes 


I Tripod 




I Porcelain Crucible 


I Stoddart Test Tube 


Clamp 


I Aluminum Dish 



302 HUMAN FOODS AND THEIR NUTRITIVE VALUE 



<^ 




Fig. 74. 



Directions for Weighing, — Place the dish or material to be 
weighed in the left-hand pan of the balance. With the forceps lay 
a weight from the weight box on the right-hand pan. 
Do not touch the weights with the hands. If the 
weight selected is too heavy, replace it with a lighter 
weight. Add weights until the pans are counter- 
poised ; this will be indicated by the needle swinging 
nearly as many divisions on one side of the scale 
as on the other. The brass weights are the gram 
weights. The other weights are fractions of a gm. The 
500, 200, 100 mg. (milligram) weights are recorded as 
0.5, 0.2, and 0.1 gm. The 50, 20, and 10 mg. weights 
as 0.05, 0.02, and o.oi gm. If the 10, and 2 gm., and 
the 200, the 100, and the 50 mg. weights are used, the 
resulting weight is 12.35 g"''s- No moist substances 
should ever come in contact with the scale pans. The weights and 
forceps should always be replaced in the weight box. Too much 
care and neatness cannot be 
exercised in weighing. 

Directions for Measuring. — 
Reagents are measured in gradu- 
ated cylinders (€ee Fig. 74). 
When the directions call for the 
addition of 5 or 10 cc. of a re- 
agent, unless so directed it is not 
absolutely necessary to measure 
the reagent in a measuring cyl- 
inder. A large test tube holds 
about 30 cc. of water. Measure 
out 5 cc. of water and transfer 
it to a large test tube. Note Fig. 75. 
its volume. Add approximately 
5 cc. of water directly to the test tube. Measure it. Repeat this 
operation until you can judge with a fair degree of accuracy the 
part of a test tube filled by 5 cc. In the experiments where a 




Pouring Reagent from 
Bottle. 



LABORATORY PRACTICE 



303 



burette is used for measuring reagents, the burette is first filled with 
the reagent by means of a funnel. The tip of the burette is allowed 
to fill before the readings are made, which are from the lowest point 
or meniscus. When reagents are removed from bottles, the stopper 




Fig. 76. — Microscope and Accessories. 
I, eye-piece or ocular ; 2, objective; 3, stage; 4, cover glass ; 5, slide; 6, mirror. 



should be held between the first and second fingers of the right 
hand (see Fig. 75). Hold the test tube or receptacle that is to 
receive the reagent in the left hand. Pour the liquid slowly until the 
desired amount is secured. Before inserting the stopper, touch it to 
the neck of the bottle to catch the few drops on the edge, thus pre- 
venting their streaking down the sides of the bottle on to the shelf. 



304 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

Replace the bottle in its proper place. Every precaution should be 
taken to prevent contamination of reagents. 

Use of the Microscope. — Special directions in the use of the micro- 
scope will be given by the instructor. The object or material to be 
examined is placed on a microscopical slide. Care should be exer- 
cised to secure a representative sample, and to properly distribute 
the substance on the slide. If a pulverized material is to be exam- 
ined, use but little and spread it in as thin a layer as possible. If a 
liquid, one or two drops placed on the slide will suffice. The mate- 
rial on the slide is covered with a cover glass, before it is placed on 
the stage of the microscope. In focusing, do not allow the object 
glass of the microscope to come in contact with the cover glass. 
Focus upward, not downward. Special care should be exercised in 
focusing and in handling the eye-piece and objective. A camePs-hair 
brush, clean dry chamois skin, or clean silk only should be used in 
polishing the lenses. Always put the microscope back in its case 



Experiment No. i 
Water in Flour 

Carefully weigh a porcelain or aluminum dish. (Porcelain must be 
used if the ash is to be determined on the same sample.) Place in it 
about 2 gm. of flour; record the weight; then place the dish in the 
water oven for at least 6 hours. After drying, weigh again, and from 
the loss of weight calculate the per cent of water in the flour. 
(Weight of flour and dish before drying minus weight of flour and 
dish after drying equals weight of water lost. Weight of water 
divided by weight of flour taken, multiplied by 100, equals the per cent 
of water in the flour.) 

How does the amount of water you obtained compare with the 
amount given in the tables of analysis? 



LABORATORY PRACTICE 305 

Experiment No. 2 

Water in Butter 

Carefully weigh a clean, dry aluminum dish, place in it about 2 
gms. of butter, and weigh again. Record the weights. Place the 
dish containing butter in the water oven for 5 or 6 hours and then 
weigh. The loss in weight represents the water in the butter. 
Calculate the per cent of water. Care must be taken to get a 
representative sample of the butter to be tested ; preferably small 
amounts should be taken with the butter trier from various parts of 
the package. 

Experiment No. 3 

Ash in Flour 

Place the porcelain dish containing flour from the preceding ex- 
periment in a m.uffle furnace and let it remain until the organic 
matter is completely volatilized. Cool, weigh, and determine the per 
cent of ash. The flour should be burned at the lowest temperature 
necessary for complete combustion. 

Experiment No. 4 

Nitric Acid Test for Nitrogenous Organic Matter 

To 3 cc. of egg albumin in a test tube add 2 cc. of HNOg (cone.) 
and heat. When cool add NH^OH. The nitric acid chemically 
reacts upon the albumin, forming yellow xanthoprotein. What 
change occurs in the appearance of the egg albumin when the 
HNOo is added? Is this a physical or chemical change? What 
is the name of the compound formed? What change occurs on 
adding NH.OH? 

Experiment No. 5 

Acidity of Lemons 

With a pipette measure into a small beaker 2 cc. of lemon juice. 
Add 25 cc. of water and a few drops of phenolphthalein indicator. 

X 



3o6 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

From the burette run in N/io KOH solution until a faint pink tinge 
remains permanently. Note the number of cubic centimeters of 
KOH solution required to neutralize the citric acid in the lemon 
juice. Calculate the per cent of citric acid. 

(i cc. of N/io KOH solution equals 0.00642 gm. citric acid. 
I cc. of HgO weighs i gm. Because of sugar and other matter in 
solution I cc. of lemon juice weighs approximately 1.03 gm.) 

I. What is the characteristic acid of lemons? 2. What is the 
salt formed when the lemon juice is neutralized by the KOH solu- 
tion? 3. Describe briefly the process for determining the acidity of 
lemon juice. 4. What per cent of acidity did you obtain? 5. How 
does this compare with the acidity of vinegar? 

Experiment No. 6 
Influence of Heat on Potato Starch Grains 

With the point of a knife scrape slightly the surface of a raw 
potato and place a drop of the starchy juice upon the microscopi- 
cal slide. Cover with cover glass and examine under the micro- 
scope. 

In the evaporating dish cook a small piece of potato, then place a 
very small portion upon the slide, and examine with the microscope. 

Make drawings of the starch grains in raw and in cooked potatoes. 

Experiment No. 7 
Influence of Yeast on Starch Grains 

Moisten a small portion of the dough prepared with yeast and 
with the stirring rod place a drop of the starchy water upon the 
slide. Cover with cover glass and examine under the micro- 
scope. 

Repeat, examining a drop of starchy water washed from flour. 

Make drawing of wheat starch grain in flour and in dough pre- 
pared with yeast. 



LABORATORY PRACTICE 307 

Experiment No. 8 

Mechanical Composition of Potatoes 

Wash one potato. Weigh, then peel, making the peeling as thin 
as possible. Weigh the peeled potato and weigh the peeling or 
refuse. Calculate the per cent of potato that is edible and the per 
cent that is refuse. 

Experiment No. 9 
Pectose from Apples 

Reduce a small peeled apple to a pulp. Squeeze the pulp through 
a clean cloth into a beaker. Add 10 cc. H^O and heat on a sand 
bath to coagulate the albumin. Filter, adding a little hot water if 
necessary. To the filtrate add 5 cc. alcohol. The precipitate is 
the pectose material. 

I. Is the pectose from the apple soluble? 2. Is it coagulated by 
heat? 3. Is it soluble in alcohol? 

Experiment No. 10 
Lemon Extract 

To 5 cc. of the extract in a test tube add an equal volume of 
water. A cloudy appearance indicates the presence of lemon oil. 
If the solution remains clear after adding the water, the extract does 
not contain lemon oil. 

Why does the extract containing lemon oil become cloudy on 
adding water? 

Experiment No. 11 

Vanilla Extract 

Pour into a test tube 5 cc. of the extract to be tested. Evaporate 
to one third. Then add sufficient water to restore the original vol- 
ume. If a brown, flocculent precipitate is formed, the sample con- 
tains pure vanilla extract. Resin is present in vanilla beans and is 
extracted in the essence. The resin is readily soluble in 50 per cent 



3o8 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

alcohol. If the alcohol is removed from the extract, the excess of 
resin is precipitated, or if free from alkali, it may be precipitated by 
diluting the original solution with twice its volume of water. Test 
the two samples and compare. 

(Adapted from Leach, " Food Inspection and Analysis.") 

1. Describe the appearance of each sample after evaporating and 
adding water. 2. Which sample contains pure vanilla extract? 
3. State the principle underlying this test. 

Experiment No. 12 
Testing Olive Oil for Cotton Seed Oil 

Pour into a test tube 5 cc. of the oil to be tested and 5 cc. of 
Halphen's Reagent. Mix thoroughly. Plug the test tube loosely 
with cotton, and heat in a bath of boiling saturated brine for 15 
minutes. If cotton seed oil is present, a deep red or orange color is 
produced. Test two samples and compare. 

Halphen's Reagent. — Mix equal volumes of amyl alcohol and car- 
bon disulphid containing about one per cent of sulphur in solution. 
(Adapted from Leach, " Food Inspection and Analysis.") 

Experiment No. 13 

Testing for Coal Tar Dyes 

Dilute 20 to 30 cc. of the material to 100 cc. ; boil for 10 minutes 
with 10 cc. of a 10 per cent solution of potassium bisulphate and 
a piece of white woolen cloth which has previously been boiled in 
a 0.1 per cent solution of NaOH and thoroughly washed in water. 
Remove the cloth from the solution, wash in boiling water, and dry 
between pieces of filter paper. A bright red indicates coal tar dye. 
If the coloring matter is entirely froin fruit, the woolen cloth will be 
either uncolored or will have a faint pink or brown color which is 
changed to green or yellow by ammonia and is not restored by 
washing. This is the Arata test. 

(Adapted, Winston, Conn. Experiment Station Report.) 



LABORATORY PRACTICE 309 

I. Describe Arata's wool test for coal tar dyes. 2. What is the 
appearance of the woolen cloth when the coloring matter is entirely 
from fruit ? 3. What effect has NH^OH upon the color ? 4. Why 
is NaOH used ? 5. Why may not cotton cloth be used instead of 
woolen ? 6. What can you say of the use of coal tar dyes in foods ? 

Experiment No. 14 
Determining the Per Cent of Skin in Beans 

Place in an evaporating dish 10 gm. of beans, 50 cc. of water, 
and I gm. of baking soda. Boil 10 minutes or until the skins are 
loosened, then drain off the water. Add cold water and rub the 
beans together till the skins slip off Collect the skins, place on a 
watch glass and dry in the water oven for 1 hour. Weigh the dried 
skins and calculate the per cent of ^' skin.'' 

I. What does the soda do? 2. What effect would hard lime- 
water have upon the skins ? 3. How does removal of skins affect 
food value of beans and digestibility? 

Experiment No. 15 
Extraction of Fat from Peanuts 

Shell three or four peanuts and with the mortar and pestle break 
them into small pieces. Place in a test tube and pour over them 
about 10 cc. of ether. Cork the test tube and allow it to stand 30 
minutes, shaking occasionally. Filter on to a watch glass and let 
stand until the ether evaporates, and then observe the fat. 

I. What is the appearance of the peanut fat ? 2. What is the 
solvent of the fat ? 3. What becomes of the ether ? 4. Why 
should the peanuts be broken into small pieces ? 

Experiment No. 16 
Microscopic Examination of Milk 
Place a drop of milk on a microscopical slide and cover with cover 
glass. Examine the milk to detect impurities, as dust, hair, refuse, 
etc. Make drawings of any foreign matter present. 



3IO HUMAN FOODS AND THEIR NUTRITIVE VALUE 

Experiment No. 17 
Formaldehyde in Cream or Milk 

To 10 cc. of milk in a casserole add 10 cc. of the acid reagent. 
Heat slowly over the flame nearly to boiling, holding the casserole 
in the hand and giving it a slight rotary movement while heating. 
The presence of formaldehyde is indicated by a violet coloration 
varying in depth with the amount present. In the absence of 
formaldehyde the solution slowly turns brown. 

Acid Reagent. — Commercial hydrochloric acid (sp.gr. 1.2) con- 
taining 2 cc. per liter of 10 per cent ferric chlorid. 

(Adapted from Leach, " Food Inspection and Analysis.") 

I. How may the presence of formaldehyde in milk be detected? 
2. Why in this test is it necessary to use acid containing ferric 
chlorid ? 3. Describe the appearance of the two samples of milk 
after adding the acid reagent and heating. 4. Which sample 
showed the presence of formaldehyde ? 

Experiment No. 18 
Gelatine in Cream or Milk 

To 20 cc. of milk or cream in a beaker add 20 cc. of acid mercuric 
nitrate and about 40 cc. of H^O. Let stand for a few minutes and 
filter. Filtrate will be cloudy if gelatine is present. 

Add I cc. of a dilute solution of picric acid — a heavy yellow 
precipitate indicates gelatine. 

Acid Mercuric Nitrate. — i part by weight of Hg, 2 parts HNO3 
(sp. gr. 1.42). Dilute 25 times with water. 

Experiment No. 19 

Testing for Oleomargarine 

Apply the following tests to two samples of the material : 
Boiling or Spoon Test. — Melt the sample to be tested — a piece 
about the size of a chestnut — in a large spoon, hastening the 



LABORATORY PRACTICE 3II 

process by stirring with a splinter. Then, increasing the heat, 
bring to as brisk a boil as possible and stir thoroughly, not neglect- 
ing the outer edges. Oleomargarine and renovated butter boil 
noisily, sputtering like a mixture of grease and water, and produce 
no foam, or but very little. Genuine butter boils with less noise and 
produces an abundance of foam. 

Waterhouse Test. — Into a small beaker pour 50 cc. of sweet 
milk. Heat nearly to boiling and add from 5 to 10 gms. of butter 
or oleomargarine. Stir with a glass rod until fat is melted. Then 
place the beaker in cold water and stir the milk until the tempera- 
ture falls sufficiently for the fat to congeal. At this point the fat, if 
oleomargarine, can easily be collected into one lump by means of 
the rod ; while if butter, it will granulate and cannot be collected. 
(From Farmers' Bui. 131, U. S. Dept. of Agriculture.) 

I. Name two simple tests for distinguishing butter and oleomar- 
garine. 2. Describe these tests. 3. Why do butter and oleomar- 
garine respond differently to these tests? 4. Are these tests based 
upon chemical or physical properties of the fats ? 

Experiment No. 20 
Testing for Watering or Skimming of Milk 

a. Fat Content of Milk by Means of Babcock Test. — Measure 
with pipette into test bottle 17.6 cc. of milk. Sample should be 
carefully taken and well mixed. Measure with cylinder 17.5 cc. 
commercial H^SO^ and add to milk in test bottle. (See Fig. 25.) 
Mix acid and milk by rotating the bottle. Then place test bottles 
in centrifugal machine and whirl 5 minutes. Add sufficient hot 
water to test bottles to bring contents up to about the 8th mark on 
stem. Then whirl bottles 2 minutes longer and read fat. Read 
from extreme lowest to highest point. Each large division as i to 2 
represents a whole per cent, each small division 0.2 of a per cent. 

b. Determining Specific Gravity by Means of Lactometer. — Pour 
150 cc. of milk into 200 cc cyhnder. Place lactometer in milk and 



312 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

note depth to which it sinks as indicated on stem. Note also tem- 
perature of milk. For each io° above 60° F. add i to the lactometer 
number, in order to make the necessary correction for temperature. 
For example, if milk has sp. gr. of 1.032 at temperature of 70°, it 
will be equivalent to sp. gr. of 1.033 ^^ 60''. Ordinarily milk has a 
sp. gr. of 1.029 to 1.034. If milk has sp. gr. of less than 1.029, ^^ 
contains less than 3 per cent fat, it may be considered watered milk. 
If the milk has a high sp. gr. (above 1-035) ^^^ ^ ^o^ content of 
fat, some of the fat has been removed. 

(For extended direction for milk testing see Snyder's " Dairy Chemistry.") 

Experiment No. 21 
Boric Acid in Meat 

Cut into very small pieces 5 gms. of meat, removing all the fat 
possible. Place in an evaporating dish with 20 to 25 cc. of water 
to which a few drops of HCl have been added and warm slightly. 
Dip a piece of turmeric paper in the meat extract and dry. A rose- 
red color of the turmeric paper after drying (turned olive by a weak 
ammonia solution) is indicative of boric acid. 

I. How may meat be tested for boric acid? 2. Why is HCl 
added to the water? 3. Why is the water containing the meat 
wanned slightly? 4. What is the appearance of the turmeric paper 
after being dipped in the meat extract and dried? 5. What change 
takes place when it is moistened with ammonia, and why? 

Experiment No. 22 
Microscopic Examination of Cereal Starch Grains 

Make a microscopic examination and drawings of wheat, corn, 
rice, and oat starch grains, comparing them with the drawings of the 
diflferent starch grains on the chart. If the material is coarse, pul- 
verize in a mortar and filter through cloth. Place a drop or two of 
the starchy water on the slide, cover with a cover glass, and ex- 
amine. 



LABORATORY PRACTICE 313 

Experiment No. 23 

Identification of Commercial Cereals 

Examine under the microscope two samples of cereal breakfast 
foods, and by comparison with the wheat, corn, and oat starch grains 
previously examined tell of what grains the breakfast foods are made 
and their approximate food value. 

Experiment No. 24 

Granulation and Color of Flour 

Arrange on glass plate, in order of color, samples of all the differ- 
ent grades of flour. Note the differences in color. How do these 
differences correspond with the grades of the flour? Examine the 
flour with a microscope, noting any coarse or dark-colored particles of 
bran or dust. Rub some of the flour between the thumb and fore- 
finger. Note if any granular particles can be detected. 

Experiment No. 25 
Capacity of Flour to absorb Water 

Weigh out 15 gms. of soft wheat flour into an evaporating dish ; 
then add from burette a measured quantity of water sufiicient to make 
a stiff dough. Note the amount of water required for this purpose. 
Repeat the operation, using hard wheat flour. 

I. Howmay the absorptive power of a flour be determined? 2. To 
what is it due? 3. Why do some flours absorb more water than 
others ? 

Experiment No. 26 
Acidity of Flour 

Weigh into a flask 20 gms. of flour and add 200 cc. distilled 
water. Shake vigorously. After letting stand 30 minutes, filter and 
then titrate 50 cc. of the filtrate against standard KOH solution, 
using phenolphthalein as indicator, i cc. of the alkali equals 0.009 
gms. lactic acid. Calculate the per cent of acid present. 



314 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

I. How may the acidity of a flour be determined? 2. The acid- 
ity is expressed in percentage amounts of what acid? 3. What per 
cent of acidity is found in normal flours? 4. What does a high 
acidity of a flour indicate ? 

Experiment No. 27 

Moist and Dry Gluten 

Weigh 30 gm. of flour into a porcelain dish. Make the flour into 
a stiff" dough. After 30 minutes obtain the gluten by washing, being 
careful to remove all the starch and prevent any losses. Squeeze the 
water from the gluten as thoroughly as possible. Weigh the moist 
gluten and calculate the per cent. Dry the gluten in the water oven 
and calculate the per cent of dry gluten. 

Experiment No. 28 
Gliadin from Flour 

Place in a flask 10 gms. of flour, 30 cc. of alcohol, and 20 cc. of 
water. Cork the flask and shake, and after a few minutes shake 
again. Allow the alcohol to act on the flour for an hour, or until 
the next day. Then filter off" the alcohol solution and evaporate the 
filtrate to dryness over the water bath. Examine the residue ; to a 
portion add a little water ; burn a small portion and observe odor. 

I. Describe the appearance of the gliadin. 2. What was the re- 
sult when water was added? 3. When burned, what was the odor of 
the gliadin, and what does this indicate? 4. What is gliadin? 

Experiment No. 29 
Bread-making Test 
Make a " sponge " by mixing together : 
12 gm. sugar, 

12 gm. yeast (compressed), 
4 gm. salt, 
175 cc. water (temp. 32° C). 



LABORATORY PRACTICE 315 

Let stand ^ hour at a temperature of 30° C. In a large bowl, mix 
with a knife or spatula 'j .'j gms. of lard with 248.6 gms. of flour. 
Then add 160 cc. of the " sponge," or as much as is needed to make 
a good stiff dough, and mix thoroughly, using the spatula. With 
some flours as small a quantity as 150 cc. of sponge may be used. 
If more moisture is necessary, add HoO. Keep at temperature of 
30"" C. Allow the dough to stand 50 minutes to first pulHng, 40 min- 
utes to second pulhng, and 30 to 50 minutes to the pan. Let it rise 
to top of pan and then bake for \ hour in an oven at a temperature 
of 180° C. One loaf of bread is made of patent flour of known 
quality as a standard for comparison, and other loaves of the flours 
to be tested. Compare the loaves as to size (cubic contents), color, 
porosity, odor, taste, nature of crust, and form of loaf. 

Experiment No. 30 

Microscopic Examination of Yeast 

On a watch glass mix thoroughly a very small piece of yeast with 
about 5 cc. of water and then with the stirring rod place a drop 
of this solution on the microscopical slide, adding a drop of very 
dilute methyl violet solution. Cover with the cover glass and 
examine under the microscope. The living active cells appear color- 
less while the decayed and lifeless ones are stained. Yeast cells are 
circular or oval in shape. (See Fig. 46.) 

(Adapted from Leach, " Food Inspection and Analysis.") 

Experiment No. 31 

Testing Baking Powders for Alum 

Place about 2 gms. of flour in a dish with \ gm. baking powder. 
Add enough water to make a dough and then 2 or 3 drops of tincture 
of logwood and 2 or 3 drops of ammonium carbonate solution. Mix 
well and observe ; a blue color indicates alum. Try the same test, 
using flour only for comparison. 



3l6 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

I. How do you test a baking powder for alum? 2. What differ- 
ence in color did you observe in the test with the baking powder 
containing alum and in that with the flour only? 3. Why is the 
(NH4)2C03 solution used? 

Experiment No. 32 
Testing Baking Powders for Phosphoric Acid 

Dissolve ^ gm. of baking powder in 5 cc. of HoO and 3 cc. 
HNO3. Pllter and add 3 cc. ammonium molybdate. Heat gently. 
A yellow precipitate indicates phosphoric acid. 

I. How do you test a baking powder for phosphoric acid? 
2. What is the yellow precipitate obtained in this test? 

Experiment No. 33 
Testing Baking Powders for Ammonia 

Dissolve i gm. of material in 10 cc. water; filter off any in- 
soluble residue and to the filtrate add 2 or 3 cc. NaOH and apply 
heat. Test the gas given off with moistened turmeric paper. If 
NH3 is present, the paper will be colored brown. Do not allow the 
paper to come in contact with the liquid or sides of the test tube. 
(Perform the tests on two samples of baking powder.) 

I. How do you test a baking powder for ammonia? 2. Why do 
you add NaOH? 3. Why must you be careful not to let the tur- 
meric paper touch the sides of the test tube or the liquid ? 

Experiment No. 34 

Vinegar Solids 

Into a weighed aluminum or porcelain dish pour 10 cc. of vinegar. 
Weigh and then evaporate over boiling water. To drive off the last 
traces of moisture dry in the water oven for an hour. Cool and 
weigh. Calculate the per cent of solids. Observe the appearance 
of the solids. Test both samples and compare. 



LABORATORY PRACTICE 317 

I. How may the per cent of solids in vinegar be determined? 
2. Describe the appearance of the solids from the good and from 
the poor sample of vinegar. 3. What is the legal standard for 
vinegar solids in your state? 

Experiment No. 35 
Specific Gravity of Vinegar 

Pour 170 cc. vinegar into 200 cc. cylinder. Place a hydrometer 
for heavy liquids (sp. gr. i to i.i) in the cylinder. Note the depth 
to which it sinks and the point registered on the scale on the stem. 
Note temperature of vinegar. Record specific gravity of vine- 
gar. 

I. What effect would addition of water to vinegar have upon its 
specific gravity? 2. What effect would addition of such material 
as sugar have upon specific gravity? 3. Why should the specific 
gravity of vinegar be fairly constant? 4. What would be the weight 
of 1000 cc. of vinegar calculated from the specific gravity? 

Experiment No. 36 
Acidity of Vinegar 

Into a small beaker pour 6 cc. of vinegar and 10 cc. of water and 
a few drops of phenolphthalein indicator. Run m standard KOH 
solution from a burette until a faint pink tinge remains permanently. 
Note the number of cubic centimeters of KOH solution required 
to neutralize the acid. Divide this number by 10, which will give 
approximately the per cent of acetic acid. 

I. How may the per cent of acidity of vinegar be determined? 
2. Why was phenolphthalein used? 3. Why was KOH used? 
4. WHiat acids does vinegar contain? 5. What is the legal re- 
quirement in this state for acetic acid in vinegar? 6. How 
did the acidity you obtained compare with this legal require- 
ment? 



3l8 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

Experiment No. 37 
Deportment of Vinegar with Reagents 

To 10 cc. of vinegar in a test tube add 8 or 10 drops of lead 
sub-acetate and shake. Observe the precipitate. Lead sub-acetate 
precipitates mainly the malic acid which is always present in cider 
vinegar. 

I. How may the presence of malic acid in a vinegar be detected? 
2. Describe the precipitate. 3. What does malic acid in a vinegar 
indicate? 

Experiment No. 38 

Testing Mustard for Turmeric 

Place I gm. of ground mustard on a small watch glass and moisten 
slightly with water. Add 2 or 3 drops of NH^OH, stirring well 
with a glass rod. A brown color indicates turmeric present in con- 
siderable quantity. 

Test a sample of good mustard and one adulterated with turmeric 
and compare the results. 

Experiment No. 39 

Examination of Tea Leaves 

Soak a small amount of tea and unroll 8 or 10 of the leaves. 
Make a drawing of a tea leaf. Observe the proportion of stems in 
each of three samples of tea ; also the relative proportion of large 
and small leaves. Observe if the leaves are even as to size and 
of a uniform color. 

Experiment No. 40 

Action of Iron Compounds upon Tannic Acid 

Make an infusion of tea by placing 3 gms. of tea in 100 cc. of hot 
water and stirring well. Filter off some of the infusion and test 
5 cc. with ferrous sulphate solution made by dissolving i gm. 
FeSO^ in 10 cc. H^O and filtering. Note the result. 



LABORATORY PRACTICE 319 

I . What change in color did you observe when the ferrous sul- 
phate solution was added to the tea infusion ? 2. What effect 
would waters containing iron have upon the tea infusion? 

Experiment No. 41 

Identification of Coffee Berries 

Examine Rio, Java, and Mocha coffee berries. Describe each. 
Note the characteristics of each kind of coff"ee berry. 

Experiment No. 42 
Detecting Chicory in Coffee 

Fill a beaker with water and place about a teaspoonful of ground 
coffee on the surface. If much of the ground material sinks and it 
imparts a dark brown color to the lower portion of the liquid, it is 
an indication of the presence of chicory. Pure coffee floats on 
water. Chicory has a higher specific gravity than coffee. 

I. How may the presence of chicory in ground coff"ee be de- 
tected? 2. Why does coff"ee float on the water while chicory sinks? 
3. What effect does chicory have upon the color of water? 

Experiment No. 43 
Testing Hard and Soft Waters 

Partially fill a large cylinder with very hard w^ater. This may be 
prepared by dissolving o.i to 0.2 gm. calcium chloride in 500 cc. 
of ordinary water. Add to this a measured quantity of soap solu- 
tion. Mix well and notice how many cubic centimeters of soap so- 
lution must be used before a permanent lather is formed, also notice 
the precipitate of ''lime soap.'' Repeat this experiment, using 
either rain or distilled water, and compare the cubic centimeters of 
soap solution used with that in former test. Repeat the test, using 
tap water. 

Soap Solution. — Scrape 10 gms. of castile soap into fine shavings 



320 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

and dissolve in a liter of alcohol, dilute with i water. Filter if not 
clear and keep in a tightly stoppered bottle. 

I. Why is more soap required to form a lather with hard water 
than with soft water? 2. What is meant by ''lime soap"? De- 
scribe its appearance. 3. How may hard waters be softened for 
household purposes ? 

Experiment No. 44 

Solvent Action of Water on Lead 

Put I gm. of clean bright lead shavings into a test tube contain- 
ing 10 cc. of distilled water. After 24 hours decant the clear liquid 
into a second test tube, acidify slightly with HCL, and add a little 
hydrogen sulphid water. A black or brownish coloration indicates 
lead in solution. 

(Adapted from Caldwell and Breneman, "Introductory Chemical Practice.") 
Under what conditions may lead pipes be objectionable? 

Experiment No. 45 

Suspended Matter in Water 

Place a drop of water on the microscopical slide, cover with cover 
glass, and examine with the microscope. Note the occurrence and 
appearance of any suspended matter in the water. 

Experiment No. 46 

Organic Matter in Water 

Pour into the evaporating dish 100 cc. H^,0 and evaporate to 
dryness over the sand bath. Ignite the solids. If the solids blacken 
when ignited, the water contains organic matter. 

Experiment No. 47 

Deposition of Lime by Boiling Water 

Boil for a few minutes about 200 cc. of water in a flask. After 
the water is cool, note any sediment of lime or turbidity of the water 
due to expelling the carbon dioxid. 



LABORATORY PRACTICE 32 1 

I. What is meant by a "hard" water? 2. What do the terms 
" temporary '' and ••' permanent ''' hardness of water mean ? 3. What 
acts as a solvent of the lime in water? 4. Why does boiling cause 
the lime to be deposited ? 

Experiment No. 48 
Qualitative Tests for Minerals in Water 

Test for Chlorids. — To 10 cc. of H2O add a few drops of HNO,, 
and 2 cc. of AgNOo. A white precipitate indicates the presence 
of chlorids, usually in the form of sodium chlorid. 

Test for Sulphates. — To 10 cc. of water add 2 cc. of dilute HCl 
and 2 cc. of BaCU. A cloudiness or the formation of a white pre- 
cipitate indicates the presence of sulphates. 

Test for Iron. — If a brown sediment is formed in water exposed 
to the air for some time, it is probably iron hydroxid. To 10 cc. of the 
water add a few drops of HNOo, heat, and then add ^ cc. of 
NH4CNS. A red color indicates the presence of iron. 

Test for CaO and MgO. — To 10 cc. of H,,0 add 5 cc. NH^H. 
If a precipitate forms, filter it off, and to the filtrate add 3 cc. NH^Cl 
and 5 cc. (NH4)2C20^. The precipitate is CaCgO^, and the filtrate 
contains the magnesia. Filter and add 5 cc. NagPO^ to precipitate 
MgNH^PO^. 

I. How would you test a water to detect the presence of organic 
matter? 2. Name some mineral impurities often found in water. 
3. Describe the test for chlorids ; for sulphates ; for iron ; for lime ; 
for magnesium. 4. Of the two classes of impurities found in water, 
which is the more harmful? 5. Name three ways of purifying 
waters known to be impure, and tell which is the most effectual. 

Experiment No. 49 

Testing for Nitrites in Water 

To 50 cc. of water in a small beaker add with a pipette 2 cc. 
of naphthylamine hydrochloride and then 2 cc. of sulphanilic acid. 



32 2 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

Stir well and wait 20 minutes for color to develop. A pink color in- 
dicates nitrites. 

Reagents Used 

Sulphanilic Acid. — Dissolve 5 gm. in 150 cc. of dilute acetic 
acid; sp. gr. 1.04. 

Naphthylamine Hydrochloride. — Boil o.i gm. of solid «-amido- 
naphthaline (naphthylamine) in 20 cc. of water, filter the solution 
through a plug of absorbent cotton, and mix the filtrate with 180 cc. 
of dilute acetic acid. All water used must be free from nitrites, and 
all vessels must be rinsed out with such water before tests are applied. 

I. -Would a water showing the presence of nitrites be a safe drink- 
ing water? Why? 2. What are nitrites ? 3. What does the pres- 
ence of nitrites indicate? 4. Are small amounts of nitrites, when 
not associated with bacteria, injurious? 



REVIEW QUESTIONS 

CHAPTER I 

General Composition of Foods 

I. To what extent is water present in foods? 2. What foods 
contain the most, and what foods the least water? 3. How does the 
water content of some foods vary with the hydroscopicity of the air? 

4. How may changes in water content of foods affect their weight? 

5. Why is it necessary to consider the water content of foods in 
assigning nutritive values? 6. How is the dry matter of a food de- 
termined? 7. Why is the determination of the water in a food often 
a difficult process? 8. What is the ash or mineral matter of a food? 
9. How is it obtained? 10. What is its source? 11. Of what is 
the ash of plants composed? 12. What part in plant life do these 
ash elements take? 13. Name the ash elements essential for plant 
growth. 14. Which of the mineral elements take the most essential 
part in animal nutrition? 15. In what form are these elements 
usually considered most valuable? 16. Why is sodium chloride or 
common salt necessary for animal life? 17. How do food materials 
diifer in ash content ? 18. Define organic matter of foods. 19. How 
is it obtained? 20. Of what is it composed? 21. Into what is the 
organic matter converted when it is burned? 22. Give the two 
large classes of organic com.pounds found in food materials. 
23. Name the various subdivisions of the non-nitrogenous com- 
pounds. 24. What are the carbohydrates? 25. Give their general 
composition. 26. What is cellulose? 27. Where is it found? 
28. What is its function in plants? 29. What is its food value? 
30. In what way may cellulose be of value in a ration? 3r. In what 
way m.ay it impart a negative value to a ration ? 32. What is starch ? 

323 



324 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

33. Where is it mainly found in plants? 34. Give the mechanical 
structure of the starch grain. 35. Why is starch insoluble in cold 
water? 36. How do starch grains from different sources differ 
in structure? 37. What effect does heat have upon starch? 
38. Define hydration of starch. 39. Under what conditions does 
this change take place? 40. What value as a nutrient does starch 
possess? 41. What is sugar? 42. How does it resemble and 
how differ in composition from starch ? 43. What are the pectose 
substances? 44. How are they affected by heat? 45. What 
food value do they possess? 46. What is nitrogen-free-extract? 
47. How is it obtained? 48. How may the nitrogen-free-extract 
of one food differ from that of another? 49. What are the fats? 
50. How do they differ in composition from the starches ? 51. Why 
does fat when burned or digested produce more heat than starch 
or sugar? 52. Name the separate fats of which animal and vege- 
table foods are composed. 53. Give some of the physical character- 
istics of fat. 54. What is the iodine absorption number of a fat? 
55. How does the specific gravity of fat compare with that of 
water? 56. Into what two constituents may all fats be separated? 
57. What is ether extract? 58. How does the ether extract in fats 
vary in composition and nutritive value? 59. What are the organic 
acids? 60. Name those most commonly met with in foods. 
61. What nutritive value do they possess? 62. What dietetic value? 
63. What value are they to the growing plant? 64. What organic 
acids are found in animal foods? 65. What are the essential oils? 
66. How do they differ from the fixed oils, or fats? 67. What prop- 
erty do the essential oils impart to foods? 68. What food value do 
they possess ? 69. What dietetic value ? 70. What are the mixed 
compounds? 71. How may a compound impart a negative value to 
a food? 72. What is the nutritive value of the non-nitrogenous 
compounds, taken as a class? ']}). Why is it necessary that 
nitrogenous and non-nitrogenous compounds be blended in a 
ration? 74. What are the nitrogenous compounds? 75. How do 
they differ from the non-nitrogenous compounds? 76. Name the 
four subdivisions of the nitrogenous compounds. 'j'j . What is 



REVIEW QUESTIONS 325 

protein? 78. What is characteristic as to its nitrogen content? 
79. What are some of the derivative products that can be obtained 
from the protein molecule ? 80 How does the protein content of 
animal bodies compare with that of plants? 81. Name the various 
subdivisions of the proteins. 82. What is albumin, and how may 
it be obtained from a food? 83. What is globulin, and how is it 
obtained from a food? 84. Give some examples of globulins. 
85. What are the albuminates, and how are they affected by the 
action of acids and alkalies? 86. What are the peptones, and how 
do they differ from the albumins? 87. How are the peptones 
produced from other proteids ? 88. What are the insoluble proteids ? 
89. Give an example. 90. Which of the proteids are found to the 
greatest extent in foods? 91. Why may proteids from different 
sources vary in their nutritive value? 92. What general change do 
the proteids undergo during digestion? 93. What is crude protein? 
94. How is the crude protein content of a food calculated? 95. Why 
is the nitrogen content of a food more absolute than the crude protein 
content? 96. What food value do the proteins possess? 97. Why 
may proteins serve so many functions in the body? 98. Why is 
protein necessary as a nutrient? 99. What is the effect of an excess 
of protein in the ration? 100. What is the effect of a scant amount 
of protein in a ration? loi. What are the albuminoids? 102. Name 
some materials that contain large amounts of albuminoids. 
103. What food value do the albuminoids possess? 104. What are 
the amids? 105. How are they formed in plants? 106. What is 
their source in animals? 107. What general changes does the 
element nitrogen undergo in plant and animal bodies ? 108. What 
is the food value of the amids? 109. What are the alkaloids ? 
no. What is their food value? in. What effect do some alkaloids 
exert upon the animal body? 112. How may they be produced in 
animal foods? 113. What general relationship exists between the 
various nitrogenous compounds? 114. Why is it essential that the 
animal body be supplied with nitrogenous food in the form of pro- 
teids? 115. Name the cycle of changes through which the element 
nitrogen passes in plant and animal bodies. 



326 HUMAN FOODS AND THEIR NUTRITIVE VALUE 



CHAPTER II 

Changes in Composition of Foods during Cooking and 
Preparation 

116. How do raw and cooked foods compare in general compo- 
sition? 117. In what ways are foods acted upon during cooking? 
118. Wliat causes chemical changes to take place during cook- 
ing? 119. What are the principal compounds that are changed 
during the process of cooking? 120. How does cooking aiTect the 
cellulose of foods? 121. What change does starch undergo during 
cooking? 122. When foods containing starch are baked, what 
change occurs? 123. How are the sugars acted upon when foods 
are cooked? 124. What effect does dry heat have upon sugar? 
125. What change occurs to the fats during cooking? 126. How 
does this affect nutritive value? 127. What changes do the pro- 
teids undergo during cooking? 128. Why does the action of heat 
affect various proteids in different ways? 129. Why are chemical 
changes, as hydration, often desiral)le in the cooking and prepara- 
tion of foods? 130. What physical changes do vegetable and ani- 
mal tissues undergo when cooked? 131. How do foods change in 
weight during cooking? 132. Why is a prolonged high temperature 
unnecessary to secure the best results in cooking? 133. To what 
extent is the energy of fuels utilized for producing mechanical and 
chemical changes in foods during cooking? 134. What effect does 
cooking have upon the bacterial flora of foods? 135. In what ways 
do bacteria exert a favorable influence in the preparation of foods? 
136. How may certain classes of bacteria exert unfavorable changes 
in the preparation of foods? 137. What are the insoluble fer- 
ments? 138. What are the soluble ferments? 139. What part do 
they take in animal and plant nutrition? 140. Define aerobic fer- 
ments. 141. Define anaerobic ferments. 142. What general rela- 
tionship exists between the chemical, physical, and bacteriological 
changes that take place in foods? 143. Why should foods also 
possess an esthetic value? 144. What kinds of colors should be 



REVIEW QUESTIONS 327 

used in the preparation of foods? 145. What processes should be 
used for removal of coloring materials from foods? 



CHAPTER III 

Vegetable Foods 

146. Give the general composition of vegetable foods as a class. 
147. How do vegetable foods differ from animal foods ? 148. Name 
some vegetables which contain the maximum, and some which 
contain the minimum percentage of protein. 149. Give the general 
composition of potatoes. 150. Of what is the dry matter mainly 
composed? 151. How much of the crude protein of potatoes is 
true protein ? 152. What ratio exists between the nitrogenous and 
non-nitrogenous compounds in the potato ? 153. Give the chemical 
composition of the potato. 154. What influence do different 
methods of boiling have upon the crude protein content of potatoes ? 
155. To what extent are the nutrients of potatoes digested and 
absorbed by the body ? 156. What value do potatoes impart to 
the ration ? 157. How do sweet potatoes differ in chemical compo- 
sition and food value from white potatoes? 158. How do carrots 
differ in composition from potatoes? 159. What is characteristic 
of the dry matter of the carrot ? 160. How do carrots and milk 
differ in composition ? 161. To what is the color of the carrot due? 
162. To what extent are the nutrients removed in the cooking of 
carrots? 163. What is the value of carrots in a ration ? 164. Give 
the characteristics of the composition of parsnips. 165. How 
does the starch of parsnips differ from that of potatoes? 166. How 
does the mineral matter of parsnips differ from that of potatoes ? 
167. How does the cabbage differ in general composition from 
many vegetables ? 168. To what extent are nutrients extracted 
in the boiling of cabbage ? 169. Give the nutritive value of 
cabbage. 170. How does the cauliflower differ from cabbage? 
171. Give the general composition of beets. 172. Give the general 
composition of cucumbers. 173. What nutritive value has lettuce ? 



328 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

174. Give the composition and dietetic value of onions. 175. How- 
does the ratio of nitrogenous and non-nitrogenous compounds in 
spinach differ from that in many other vegetables ? 1 76. Give the 
general composition and nutritive value of asparagus. 177. How 
much nutritive material do melons contain ? 178. What are the 
principal compounds of tomatoes ? 179. Wha't nutrients do they 
supply to the ration ? 180. In the canning of tomatoes, why is it 
desirable to conserve the juices ? 181. How does sweet corn dif- 
fer in composition from fully matured corn ? 182. What nutritive 
value does the egg plant possess ? 183. What are the principal 
nutrients of squash ? 184. WHiat nutritive material does celery 
contain? 185. To what does celery owe its dietetic value? 
186. Why are vegetables necessary in a ration ? 187. Why is it not 
possible to value many vegetable foods simply on the basis of per- 
centage of nutrients present? 188. Name the miscellaneous com- 
pounds which many vegetables contain, and the characteristics 
which these may impart. 189. Why is it necessary to consider the 
sanitary conditions of vegetables ? 190. How do canned vegeta- 
bles differ in composition and food value from fresh vegetables ? 
191. What proportion of vegetables is refuse and non-edible 
parts ? 192. Why is it necessary to consider the refuse of a food in 
determining its nutritive value ? 



CHAPTER IV 

Fruits 

193. To what extent do fruits contain water and dry matter? 
194. Give the general composition of fruits. 195. What compounds 
impart taste and flavor? 196. How much nutrients do fruits add to 
a ration? 197. Why is it not right to determine the value of fruits 
entirely on the basis of nutrients ? 1 98 . Give the general composition 
of apples? 199. What compound is present to the greatest extent 
in the dry matter of apples? 200. How do apples differ in com- 
position? 201. Give the general physical composition of oranges. 



REVIEW QUESTIONS 329 

202. What nutrients are present to the greatest extent in oranges? 

203. How do lemons differ in composition from oranges? 204. How 
does grape fruit resemble and how differ in chemical composition 
from oranges and lemons? 205. What are the main compounds in 
strawberries? 206. In what ways are strawberries valuable in a 
ration? 207. Of what is grape juice mainly composed ? 208. What 
acid is in grapes, and what is its commercial value? 209. To what 
are the differences in flavor and taste due? 210. How do ripe olives 
differ in composition from green olives? 211. What is the food 
value of the olive? 212. What physiological property does olive oil 
have? 213. What is the principal nutrient in peaches? 214. What 
compounds give flavor to peaches? 215. Of what does the dry 
matter of plums mainly consist? 216. How do plums differ in com- 
position from many other fruits ? 217. What are prunes? What is 
their food value? 218. How do dried fruits differ in composition 
from fresh fruits? 219. What should be the stage of ripeness of 
fruit in order to secure the best results in canning? 220. How do 
canned fruits differ in composition and nutritive value from fresh 
fruits? 221. To what extent are metals dissolved by fruit juices? 
222. Why should tin in which canned goods are preserved be of 
good quality? 223. What preservatives are sometimes used in the 
preparation of canned fruits? 224. What is the objection to their 
use? 225. Why are fruits necessary in the ration? 226. What 
change does heat bring about in the pectose substances of fruits? 



CHAPTER V 

Sugar, Molasses, Sirups, Honey, and Confections 

227. What is sugar? 228. From what sources are sugars ob- 
tained ? 229. Name the two divisions into which sugars are divided. 
230. How are sugars graded commercially? 231. What per cent 
of purity has granulated sugar? 232. How is the coloring material 
of sugar removed? 233. How is sugar treated to make it whiter? 
234. What value as a nutrient does sugar possess? 235. Why 



330 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

should sugar be combined with other nutrients ? 236. What foods 
contain appreciable amounts of sugar? 237. Why is an excessive 
amount of sugar in a ration undesirable? 238. Does sugar possess 
more than condimental value? 239. What is the average quantity 
of sugar consumed in this country? 240. What is maple sugar? 
241 . How does it differ in composition from other sugar? 242. How 
is adulterated maple sugar detected? 243, To what extent is gran- 
ulated sugar adulterated? 244. Why is it not easily adulterated? 
245. What are the dextrose sugars? 246. How do they differ 
chemically from sucrose? 247. What is the inversion of sugar? 
248. In what way does acid act upon sugar? 249. How are the 
acid products removed? 250. What is the food value of glucose? 
251. What is molasses? 252. How is it obtained? 253. Of what 
is it composed? 254. What gives taste and flavor to molasses? 
255. How may molasses act upon metalware? 256. What is the 
food value of molasses? 257. What is sirup? 258. Name three 
kinds of sirup, and mention materials from which they are pre- 
pared. 259. What is the polariscope, and how is it employed in 
sugar work? 260. What is honey? 261. How does it differ in 
composition from sugar? 262. How is strained honey adulterated? 

263. What materials are used in the preparation of confections? 

264. What changes take place in their manufacture? 265. What 
materials are used for imparting color? 266. What can you say in 
regard to the coal tar colors? 267. What should be the position of 
candy in the dietary? 268. What can you say of the comparative 
value of cane and beet sugar? 269. How do the commercial grades 
of sugar compare as to nutritive value? 270. What are some of 
the impurities in candy? 271. What is saccharine? 272. What 
are its properties? 

CHAPTER VI 

Legumes and Nuts 

273. What nutrients do the legumes contain in comparatively 
large amounts? 274. How does the amount of this nutrient com- 



REVIEW QUESTIONS 33 1 

pare with that found in meats? 275. Why are legumes valuable 
crops in general farming and for the feeding of farm animals? 
276. Give the general composition of beans. 277. How do beans 
compare in protein content with cereals ? 278. How does the protein 
of beans differ from that of many other food materials? 279. To what 
extent are the nutrients of beans digested? 280. What influence 
does the combination of beans with other foods have upon digesti- 
bility? 281. What influence does removal of skins have upon 
digestibility? 282. In what part of the digestive tract are beans 
mainly digested? 283. How does the cost of the nutrients in beans 
compare with that of the nutrients in other foods? 284. How do 
string beans differ from green beans? 285. Give the general com- 
position, digestibility, and nutritive value of peas. 286. What 
can you say of the use of copper 'sulphate in the preparation of 
canned peas? 287. What nutrients do peanuts contain in large 
amounts? 288. Give the general composition of nuts. 289. What 
are the characteristics of pistachio? 290. Give the general com- 
position of the cocoanut. 291. What is cocoanut butter? 292. To 
what extent may nuts contribute to the nutritive value of a ra- 
tion? 



CHAPTER VII 

Milk and Dairy Products 

293. What can you say as to the importance of dairy products in 
the dietary? 294. Give the general composition of milk. 295. What 
compound in milk is most variable? 296. To what extent are 
the nutrients in milk digestible? 297. What influence does milk 
have upon the digestibility of other foods? 298. Why is cheese 
cured in cold storage? 299. How can the tendency of a milk diet 
to produce costiveness be overcome? 300. Why is it necessary to 
consider the sanitary condition of milk? 301. What factors in- 
fluence the sanitary condition of milk? 302. What is certified milk? 
303. What is pasteurized milk? 304. How can milk be pasteurized 



332 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

for family use ? 305. What is tyrotoxicon ? 306. Wliat is its 
source in milk? 307. To what is the color of milk due? 308. To 
what extent is color associated with fat content ? 309. What 
causes souring of milk? 310. What change occurs in the milk 
sugar? 311. What are the most favorable conditions for the sour- 
ing of milk ? 312. What are some of the preservatives used in milk. 
313. What objection is urged against their use? 314. What is con- 
densed milk? 315. What is buttermilk, and what dietetic value has 
it? 316. How does goats' milk differ from cows' milk ? 317. What 
is koumiss, and how is it prepared? 318. What are the pre- 
pared milks? 319. How does human milk differ in composition 
from cows' milk? 320. Give the nutritive value of skim milk. 
321. What content of fat should cream contain? 322. In what 
ways is milk adulterated ? 323. How are these adulterations de- 
tected ? 324. Give the general composition of butter. 325. What 
is the maximum amount of water that a butter may contain without 
being considered adulterated ? 326. What can you say in regard 
to the digestibility of butter ? 327. How is butter adulterated ? 
328. How does oleomargarine compare in digestibility and food value 
with butter ? 329. What is the food value of butter ? 330. How 
does cheese differ in composition from butter? 331. Give the 
general composition of cheese. 332. To what are the flavor and 
odor of cheese due ? 333. Why is cheese ripened ? 334. What 
chemical changes take place during ripening ? 335. To what extent 
are the nutrients of cheese digested ? 336. Why is cheese some- 
times considered indigestible? 337. To what extent do the nu- 
trients of different kinds of cheese vary in digestibility ? 338. How 
does cheese compare in nutritive value and cost with meats ? 
339. What is cottage cheese ? 340. What is Roquefort cheese ? 
341. Name four kinds of cheese, and say to what each owes 
its individuality. 342. How is cheese adulterated ? 343. Why 
are dairy products in older agricultural regions generally cheaper 
than meats ? 



REVIEW QUESTIONS 333 

CHAPTER VIII 

Meats and Animal Food Products 

344. Give the general composition of meats. 345. How do meats 
differ in chemical composition from vegetable fcods ? 346. What 
is the principal non-nitrogenous compound of meats, and what 
of vegetables ? 347. Name the different classes of proteins in 
meats. 348. Which class is present in largest amounts ? 349. To 
what extent are amid compounds present in meats ? 350. What 
characteristics do amids impart to meats ? 351. How are alkaloids 
produced in meats ? 352. In what ways does the lean meat of 
different kinds of animals vary chemically and physically ? 353. Give 
the general composition of beef. 354. What relationship ex- 
ists between the fat and water content of beef? 355. How much 
refuse have meats ? 356. In what forms are the ash elements 
(mineral matter) present in meats ? 357. How does veal differ in 
composition from beef ? 358. What general changes in composi- 
tion occur as animals mature? 359. How do these compare with 
the changes that take place when plants ripen and seeds are pro- 
duced ? 360. How does mutton vary in composition from beef ? 
361. How does it compare in food value with beef ? 362. How do 
lamb and mutton differ in composition ? 363. To what extent do 
the various cuts differ in composition ? 364. How do the more ex- 
pensive cuts of lamb compare in nutritive value with the less 
expensive cuts ? 365. How does pork differ in composition from 
other meats ? 366. Give the general composition of ham. 
367. Give the composition and nutritive value of bacon. 368. How 
does bacon compare in food value with other meats ? 369. How 
does the character of the fat influence the composition and taste of 
the meat ? 370. What influences the texture or toughness of 
meats ? 371. How do cooked meats compare in composition with 
raw meats ? 372. To what extent are nutrients lost in the boiling 
of meats ? 373. What influence does the temperature of the water 



334 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

in which the meat is placed for cooking have upon the amount of 
nutrients extracted ? 374. To what is the shrinking of meats in 
cooking due ? 375. Of what does meat extract mainly consist ? 
376. To what do beef extracts owe their flavor ? 377. What is 
their food value ? 378. What is their dietetic value ? 379. What 
is lard ? 380. How does it differ in composition from other fats ? 

381. What is imparted to meats during the smoking process ? 

382. Why is saltpeter used in the preservation of meats ? 383. Do 
vegetable foods contain nitrates and nitrites ? 384. How does 
poultry resemble and how differ in composition from other meat ? 
385. Give the characteristics of sound poultry. 386. Give the 
general composition of fish. 387. How does the flesh of different 
kinds of fish vary in composition? 388. What influence does salt- 
ing and preservation have upon composition ? 389. How do fish 
and meat compare in digestibility? 390. How does the mineral 
matter and phosphate content of fish compare with that of other 
foods? 391. What are the main nutrients in oysters? 392. Give 
the general food value of oysters. 393. What is meant by the fatten- 
ing of oysters ? 394. What effect does the character of the water used 
in fattening have upon the sanitary value ? 395. Give the general 
composition of the egg. 396. How do diff'erent parts of the egg 
differ in composition ? 397. How does the egg differ in composi- 
tion from the potato ? 398. Is color an index to the composition 
of the egg ? 399. What effect does cooking have upon the compo- 
sition of the egg? 400. What factors influence the flavor of eggs ? 

401. How do diff'erent ways of cooking affect the digestibility? 

402. Under what conditions can eggs be used economically in the 
dietary? 403. Why should eggs be purchased and sold by weight? 

404. How do canned meats differ in composition from fresh meats? 

405. How do the nutrients of canned meats compare in cost with 
those of fresh meat? 406. What are the advantages of canned 
meats over fresh meats ? 407. What are some of the materials used 
in the preservation of meats? 



REVIEW QUESTIONS 335 



CHAPTER IX 

Cereals 

408. How are the cereals milled? 409. What are the cereals 
most commonly used for food purposes? 410. Give the general 
composition of cereals as a class. 411. What are the main nutri- 
ents in corn preparations? 412. What influence does the more 
complete removal of the bran and germ of corn have upon its diges- 
tibility? 413. How does the cost of nutrients in corn compare 
with other foods ? 414. Why is corn alone not suitable for bread- 
making purposes? 415. Why should corn be combined in a ration 
with foods mediumly rich in protein? 416. What change takes 
place in corn meal from long storage? 417. Give the characteris- 
tics and composition of oat preparations. 418. How does removal 
of the oat hull affect the composition of the product? 419. To 
what extent do the various oat preparations on the market differ in 
composition and food value ? 420. Do oats contain any special 
alkaloidal or stimulating principle? 421. Why should oatmeal 
receive longer and more thorough cooking than many other 
foods? 422. To what extent are the nutrients in oatmeal digested? 
423. How do wheat preparations differ in general composition 
from corn and oat preparations? 424. What influence upon the 
composition of the wheat breakfast foods has partial or complete 
removal of the bran ? 425. What is the effect upon their digesti- 
bility and nutritive value? 426. What are the special diabetic 
flours, and how are they prepared? 427. What are the wheat mid- 
dlings breakfast foods, and how do they compare in digestibility and 
food value with bread? 428. How do they differ mechanically? 

429. How does barley differ from wheat in general composition? 

430. What is barley water, and what nutritive material does it 
contain? 43/. What cereal does rice resemble in composition? 
432. With what food materials should rice be combined to make 
a balanced ration? 433. What can you say as to comparative ease 



336 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

and completeness of digestibility of rice? 434. Why are cereals 
valuable in the ration? 435. In what way do they take a me- 
chanical part in digestion? 436. What are predigested breakfast 
foods? 437. How would you determine the general nutritive value 
of a breakfast food, knowing the kind of cereal from which it was 
prepared? 438. To what extent are cereals modified or changed in 
composition by cooking? 439. To what extent are the nutrients of 
cereal foods digested and absorbed by the body? 440. To what ex- 
tent do the cereals supply the body with mineral matter? 441. How 
does the phosphate content of cereals compare with that of meats 
and milk? 



CHAPTER X 

Wheat Flour 

442. Why is wheat flour especially adapted to bread-making pur- 
poses ? 443. To what extent may wheat vary in protein content ? 
444. What are spring wheats ? 445. What are winter wheats ? 
446. Give the general characteristics of each. 447. What are gluti- 
nous wheats? 448. What are starchy wheats? 449. Name the 
different proteids in wheat flour. 450. About how much starch does 
wheat flour contain? 451. What other carbohydrates are also pres- 
ent? 452. What is the roller process of flour milling? 453. What 
is meant by the first break? 454. How are the different products of 
the wheat kernel separated? 455. What is meant by middlings 
flour? 456. What is break flour? 457. What is patent flour? 
458. Name the high grade flours. 459. Name the low grade flours. 
460. How are the impurities removed from wheat flour? 461. What 
per cent of the wheat kernel is returned as flour? As offals ? 
462. What becomes of the wheat germ during milling? 463. What 
sized bolting cloths are used in milling? 464. What is graham 
flour? 465. How does it differ in mechanical and chemical com- 
position from white flour ? 466. What is entire wheat flour? 
467. How does it differ in physical and chemical composition from 



REVIEW QUESTIONS 337 

white flour? 468. What effect has the refining of flour upon the ash 
content? 469. How do low and high grade flours differ in chemical 
composition? 470. How do the wheat offals differ in composition 
from the flour? 471. What are the factors which influence the com- 
position of flours ? 472. What effect does storage have upon the 
bread-making value of flour? 473. What change takes place when 
new wheat is stored in an elevator? 474. What is durum wheat flour, 
and how does it differ from other flour? 475. What gives flour its 
color? 476. Why is color an index of grade? 477. How is the 
color of a flour determined ? 478. How do flours differ in granula- 
tion? 479. How does the granulation affect the physical properties 
of flour? 480. How is the granulation of flour approximately deter- 
mined? 481. How is the absorptive capacity of a flour determined ? 
482. What factors cause a variation in the capacity of flours to 
absorb water? 483. Give the characteristics of a good gluten. 
484. What causes unsound flours? 485. How is the bread-making 
value of a flour determined ? 486. How are flours bleached ? 
487. How does bleaching affect the chemical composition of 
flour ? 488. What influence does bleaching have upon bread- 
making value? 489. Traces of what compounds are formed during 
bleaching ? 490. Are these compounds injurious to health ? 
491. What effect does bleaching have upon the color of fiber and 
debris particles in flour? 492. Is it possible to bleach low grade 
flours and cause them to resemble high grade flours? 493. Are 
flours usually adulterated ? 494. Why ? 495. How would mineral 
adulterants be detected ? 496. How would the presence of other 
cereals be detected ? 497. How does flour compare in nutritive 
value with other foods? 498. How does the cost of flour compare 
with that of other foods ? 499. What causes flours to vary so in 
bread-making value ? 500. Why may flours produced from the 
same type of wheat vary slightly in character from year to year ? 
501. What relationship exists between the nutritive and bread- 
making value of a flour? 



338 HUMAN FOODS AND THEIR NUTRITIVE VALUE 



CHAPTER XI 

Bread and Bread Making 

502. Define leavened and unleavened bread. 503. Why is yeast 
used in bread making ? 504. Give the characteristics of a good loaf 
of bread. 505. Why is flour used for bread making purposes? 
506. Name the eight chemical changes that take place during bread 
making. 507. To what extent do losses in dry matter occur during 
bread making ? 508. What compounds suffer losses during bread 
making? 509. What is yeast ? 510. What chemical changes does 
it produce ? 511. What becomes of these products during bread 
making^ 512. How is compressed yeast made ? 513. What part 
does the alcohol take in bread making? 514. What temperature 
is reached in the interior of the loaf during bread making ? 
515. Through what chemical changes does starch pass during 
bread making? 516. To what extent are soluble carbohydrates 
formed? 517. In what way is starch acted upon mechanically? 

518. Explain the structure of the starch grains in flour and in 
dough after they have been acted upon by the yeast ferments. 

519. To what extent are acids produced in bread making? 

520. What becomes of the acids formed? 521. How may the acids 
thus developed affect the properties of other chemical compounds ? 

522. To what extent are volatile carbon compounds, other than 
carbon dioxid and alcohol, liberated during bread making ? 

523. What changes occur to the various proteids during the process 
of bread making ? 524. Why do flours vary in quality of gluten ? 
525. To what extent do losses of nitrogen occur during bread 
making? 526. How much of the total nitrogen of flour is present as 
proteids ? 527. How is the fat of flour affected during the process of 
bread making? 528. What eff"ect does the addition of 10 per cent of 
wheat starch to flour have upon the size of the loaf? 529. What effect 
does the addition of 10 per cent of wheat gluten to flour have upon the 
size of the loaf ? 530. What relationship exists between gluten con- 
tent and capacity of a flour to absorb water? 531. Give the general 



REVIEW QUESTIONS 339 

composition of bread. 532. What factors influence its composition? 
533- What effect does the use of skim milk and lard in bread 
making have upon composition? 534. How does the temperature 
of the flour influence the bread-making process? 535. Why is it 
necessary to vary the process of bread making in order to get the 
best results with different kinds of flour? 536. To what extent are 
the nutrients of bread digested? 537. How does graham bread 
compare in digestibility with white bread? 538. How do graham 
and entire wheat breads compare in nutritive value with white bread? 
539. What value do graham and entire wheat breads have in the 
dietary? 540. Why is white bread generally preferable in the 
dietary of the laboring man? 541. How do graham and entire 
w^heat flours compare in chemical composition with white flour? 
542. How do they compare in mechanical composition? 543. To 
what is the difference in digestibility supposed to be due ? 544. Are 
graham and entire wheat breads necessary in a ration as a source of 
mineral elements? 545. What is the main difference in composition 
between old and new bread? 546. How do different kinds of bread 
made from the same flour compare in composition and nutritive 
value? 447. How does toast differ in composition from bread? 

548. What influence does toasting have upon digestibility? 

549. What is gained by toasting bread? 550. How does bread 
compare in nutritive value with other cereal foods? 551. How does 
bread compare in nutritive value with animal foods ? 



CHAPTER XII 

Baking Powders 

552. What is a baking powder? 553. What are the two kinds 
of materials which baking powders contain? 554. Name the differ- 
ent types of baking powders. 555, How does baking powder differ 
in its action from yeast? 556. What are the cream of tartar baking 
powders? 557. What is the nature of the residue which they leave? 
558. What are the phosphate baking powders? 559. What is the 



340 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

nature of the residue which they leave? 560. Why is the mineral 
phosphate not considered equally valuable with that naturally present 
in foods? 561. What are the alum baking powders? 562. What 
residue is left from the alum powders? 563. Which of the three 
classes of baking powders is considered the least objectionable? 
564. Why is a new baking powder preferable to one that has been 
kept a long time? 565. Why should baking powders be kept in tin 
cans, and not in paper? 566. Why are fillers used in the manufac- 
ture of baking powders? 567. How may a baking powder be pre- 
pared at home? 568. How does such a baking powder compare in 
cost and efficiency with those purchased in the market? 



CHAPTER XIII 

Vinegars, Spices, and Condiments 

569. What is vinegar? 570. How is it made? 571. Give the 
three chemical changes that take place in its preparation. 572. Why 
is air necessary in the last stage of the process? 573. What ferments 
take part in the production of vinegar? 574. What is malt vinegar? 
575. What materials other than apples can be used in the prepa- 
ration of vinegar? 576. Give the characteristics of a good vinegar. 
577. In what ways are vinegars adulterated? 578. What food value 
has vinegar ? 579. Why should vinegars not be stored in metalware ? 
580. What dietetic value has vinegar? 581. To what materials do 
the spices owe their value? 582. What is pepper? 583. What is 
the difference between white and black pepper? 584. What com- 
pounds give pepper its characteristics? 585. How are peppers adul- 
terated? 586. What is mustard ? 587. Give its general composition. 
588. How is it adulterated? 589. What is ginger? 590. How is 
it prepared for the market? 591. Give its general composition. 
592. What is cinnamon? 593. What is cassia? 594. What gives 
these their taste and flavor? 595. What are cloves? 596. Howare 
they prepared? 597. What is mace? 598. What is nutmeg? 



REVIEW QUESTIONS 34I 

599. Do the spices have any food vakie? 600. What is their dietetic 
value? 601. Why is excessive use of some of the spices objection- 
able? 



CHAPTER XIV 

Tea, Coffee, Chocolate, and Cocoa 

602. What is tea? Name the two plants from which it is ob- 
tained, the countries where each grows best, and the number of 
flushes each yields. 603. Upon what does the quality and grade of 
tea depend? 604. Give differences in the preparation and composi- 
tion of green and black teas. 605. The characteristic flavor of tea 
is imparted by what compound? 606. To what compound are its 
peculiar physiological properties due? 607. What can you say of 
the protein in tea as to amount and food value? 608. Why should 
tea — especially green tea — be infused for a very short time, never 
boiled ? 609. What effect has tannin upon the digestion of proteids ? 
610. What three points are considered in judging a tea? 611. What 
is the most common form of tea adulteration? 612. Describe the 
coffee plant and fruit, and its method of preparation for market. 
613. What is the difference in the chemical composition of tea 
and coffee? 614. Name the characteristic alkaloid of coffee. 
How does it compare with theine? 615. Why may coffee not be 
considered a food? 616. Tell different ways in which coftee may be 
adulterated. 617. Which is more commonly practiced, tea or coffee 
adulteration? Why? 618. How may real coffee be distinguished 
from chicory? Why? 619. Name the three kinds of coffee in 
general use. Give distinguishing features of each. Which is usu- 
ally considered best? 620. From what are cocoa and chocolate 
obtained? 621. Give the two methods of preparing cocoa. 
622. What alkaloid similar to the theine and caffeine of tea and 
coffee is present in cocoa and chocolate ? 623. What is the difference 
in preparation of cocoa and chocolate ? 624. What are cereal coffee- 
substitutes? 625. What nutritive value have they? 626. How do 



342 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

they differ in composition from coffee? 627. To what extent does 
cocoa add to the nutritive value of a ration? 628. What is plain 
chocolate? 629. Why do chocolate preparations vary so widely 
in composition? 630. What treatment is given to the cocoa bean 
in its preparation for commerce? 631. What treatment is some- 
times given to prevent separation of the cocoa fat? 632. In 
what ways may cocoa and chocolate preparations be adulter- 
ated? 



CHAPTER XV 

Digestibility of Foods 

633. Define the term nutrient. 634. Do all the nutrients of 
food have the same degree of digestibility? 635. What is a diges- 
tion coefficient? 636. How is the digestibility of a food deter- 
mined? 637. What volatile products are formed during the diges- 
tion of food? 638. Define digestible protein; digestible carbohy- 
drates, digestible fat. 639. What is the available energy of a ration ? 
640. How is it determined? 641. How do the nutrients, pro- 
tein, fat, and carbohybrates, compare as to available energy? 

642. Why is it necessary to consider the caloric value of a ration? 

643. Is the protein molecule as completely oxidized in the body 
as starch or fat? 644. What residue is left from the digestion of 
protein? 645. What part do the soluble ferments take in diges- 
tion? 646. To what extent are the nutrients of animal foods di- 
gested? 647. Which nutrient, protein or fat, is the most completely 
digested? 648. How do vegetable foods compare in digestibility 
with animal foods? 649. What effect does cellulose have upon 
digestibility? 650. Which of the nutrients of vegetables, protein or 
carbohydrates, is more completely digested? 651. What mechani- 
cal value may cellulose have in a ration? 652. Why must bulk be 
considered in a ration, as well as nutrient content? 653. Name 
the eight most important factors influencing the digestibility of 
foods. 654. To what extent does the combination of foods affect 



REVIEW QUESTIONS 343 

the digestibility of the nutrients? 655. Why does a mixed ration 
give better results than when only a single food is used? 656. How 
does the amount consumed affect the completeness of the digestive 
process? 657. To what extent does the method of preparing food 
affect digestibility? 658. What is gained, so far as digestibility is 
concerned, by the cooking of foods? 659. To what extent does 
the mechanical condition of food affect its digestibility? 660. Why 
is it desirable to have some coarsely granulated foods in a ration ? 
661. Why should the ration not be composed exclusively of finely 
granulated foods ? 662. Why is some coarsely granulated food 
more essential in the dietary of the sedentary than in the dietary 
of the laborer ? 663. How does palatability affect the digestive 
process ? 664. Do psychological processes in any way affect 
digestion? 665. What physiological properties do some foods 
possess ? 666. To what are these physiological properties due ? 

667. To what extent is individuality a factor in digestion ? 

668. To what extent does digestibility differ with individuals? 

669. Why do some foods affect individuals in different ways ? 

670. Why is it necessary that the quantity, quality, and character 
of the food should vary with different individuals ? 671. In what 
different ways is the expression "digestibility of a food'' used? 
672. Why is it necessary to consider the digestibility of food, as 
well as its composition ? 673. Does the digestibility of a food nec- 
essarily indicate the economic uses that will be made of it by the 
body? 674. How is it possible for one food containing 10 per 
cent of digestible protein, and other nutrients in like amounts, to be 
more valuable than another food with the same per cent of digesti- 
ble protein and other nutrients? 675. How is it possible for one 
food to contain less total protein than another food and yet be more 
valuable from a nutritive point of view ? 676. Why is it necessary 
to consider the mechanical condition of a food and its combination 
with other foods, as well as its chemical composition? 677. What 
effect does lack of a good supply of air have upon the completeness 
of the digestion process ? 678. In what ways does the digestion of 
food resemble the combustion of fuel ? 679. What is gained by a 



344 HUMAN FOODS AND THEIR NUTRITIVE VALUE . 

study of the digestibility of foods ? 680. Why may two foods of 
the same general character give different results when used for nu- 
tritive purposes? 

CHAPTER XVI 

Comparative Cost and Value of Foods 

68 r. To what extent do the nutritive value and the market price 
of foods vary ? 682. How is the value of one food expressed in 
terms of another food ? 683. How determine the amount of nutri- 
ents that can be procured in a food for a given sum of money ? 
684. How compare the amounts of nutrients that can be procured 
in two foods for a given sum of money ? 685. How is it possible 
to determine approximately which of two foods is cheaper, when the 
price and composition of the foods are known ? 686. To what 
nutrient is preference usually given in assigning a value to a food ? 
687. When the difference in this nutrient between two foods is 
small, then the preference is given to what nutrients ? 688. At 
ordinary prices, what are the cheapest vegetable foods ? 689. What 
are among the cheapest animal foods ? 690. Why is it not possible 
to determine the value of a food absolutely from its composition and 
digestibility ? 691. Why is it necessary to consider the physical 
as well as the chemical composition of foods? 692. What propor- 
tion of the income of the laboring man is usually expended for 
tood ? 693. What are the most expensive foods ? 694. What 
toods furnish the largest amount of nutrients at the least cost ? 



CHAPTER XVII 

Dietary Studies 

695. What is a dietary study? 696. How is a dietary study 
made ? 697. What is the value of the dietary study of a family ? 
698. To what extent does the protein in the dietary range ? 



REVIEW QUESTIONS 345 

699. Why is a scant amount of protein in a ration undesirable ? 

700. Why IS an excess of protein in the ration undesirable ? 

701. What are dietary standards ? 702. How are such standards 
obtained ? 703. Why is it desirable in a ration to secure the pro- 
tein and other nutrients from a variety rather than from a few foods ? 

704. Why is it necessary to consider the caloric value of a ration? 

705. How is this determined ? 706. What is a wide nutritive 
ratio? 707. What is a narrow nutritive ratio? 708. Why should 
the amount of nutrients consumed vary with the work performed? 

709. How should the nutrients be apportioned among the meals? 

710. What are some of the most common dietary errors? 

711. What analogy exists between human and animal feeding? 

712. What is gained by the rational feeding of both humans and 
animals? 713. What use can be made of the results of dietary 
studies for improvement of the dietary? 714. Why is it not pos- 
sible for animal foods to compete in economy with cereal and vege- 
table foods? 715. Is a well-balanced ration and one containing 
an ample supply of nutrients necessarily an expensive ration? 
716. Show how it is possible for one family to spend less money 
for food than another family, and yet secure more digestible nutrients 
and energy. 717. What are some of the most erroneous ideas as to 
food values? 718. Why is it necessary to consider previously 
acquired food habits in the selection of foods? 719. In general, 
what portion of the nutrients of a ration should be derived from 
vegetable foods, and what portion from meats? 720. To what 
extent may a ration vary from the dietary standards? 721. Why 
are some inexpensive foods often expensive when prepared for the 
table? 722. What are some of the ways in which the cost of a ration 
can be decreased without sacrificing nutritive value? 723. Why do 
different nationalities acquire distinct food habits ? 724. Why is 
it not possible to make sudden and radical changes in the dietary ? 
725. Why is it not possible for a dietary which gives ample satis- 
faction for one class of people to be applied to another class with 
equal satisfaction? 726. What relationship exists between the die- 
tary of a nation and its physical development? 727. What rela- 



346 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

tionship exists between dietary habits and mental development and 
vigor? 728. Why is it unnecessary and undesirable to regulate 
absolutely the amount of nutrients consumed in the daily ration? 
729. What is the general tendency as to quantity of food and 
amount of nutrients consumed? 730. Why do people of sedentary 
habits require a different dietary from those pursuing active, out-of- 
door occupations? 

CHAPTER XVIII 

Rational Feeding of Man 

731 . What IS the object of the rational feeding of man? 732. On 
what IS it based? 733. How does it compare with the rational feed- 
ing ot animals? 734. What is a standard ration? 735. How is it 
determined? 736. To what extent may the nutrients of a ration 
vary from the standard? 737. How do you combine foods to form 
a balanced ration? 738. What foods are valuable for supplying 
protein? 739. What foods supply fats? 740. What foods are rich 
in carbohydrates? 741. What other requisites should a ration have 
in addition to supplying the necessary nutrients? 742. Why is it 
necessary to consider the caloric value of a ration? 743. If a ration 
contained an excess of carbohydrates and a scant amount of protein, 
how could it be improved? 744. How do you calculate the nutrients 
in a traction of a pound of food? 745. Give the amounts of the 
common food materials, as potatoes, bread, butter, milk, and cheese, 
ordinarily combined to form a ration. 746. To what extent may 
foods differ in composition from the average analysis given? 
747. What foods are subject to the greatest and what foods to 
the least variation ? 

CHAPTER XIX 

Water 

748. Why is water regarded as a food? 749. Does it enter 
chemically into the composition of plants? Of animals? 750. In 



REVIEW QUESTIONS 347 

addition to serving as a food, why is water necessary for life pro- 
cesses? 751. In what ways may water be improved? 752. What 
are the most common forms of impurities? 753. What are the 
mineral impurities of w^ater? 754. What is their source? 755. What 
effect do some of these minerals have upon the value of the water? 
756. What causes some waters to dissolve limestone? 757. What 
are permanently hard waters? 758. To what is temporary hardness 
in water due? 759. What is the best way to remove mineral matter 
from water? 760. What are the organic impurities of water? 
761. What are the sources of the organic impurities? 762. What 
change does the organic matter of water undergo? 763. What be- 
comes of the nitrogen of the organic matter? 764. What does the 
presence of nitrates in water indicate ? TJitrites? 765. What is the 
total solid matter of a water, and how is it obtained? 766. Define 
the terms free ammonia; albuminoid ammonia. 767. What does 
the presence of chlorine in a surface well water indicate? 768. Ex- 
plain natural purification of water. 769. Can natural purification 
always be relied upon? 770. Why does the character of the drink- 
ing water affect health? 771. What diseases are mainly caused by 
impure drinking water? 772. With what materials in water are the 
disease-producing organisms associated? 773. Why should a water 
of questionable purity be boiled? 774. State how the boiling should 
be done, to be effective. 775. Why should boiled water receive 
further care in its storage? 776. What effect does improvement 
of the water supply of a city have upon the death rate? ']']']. How 
may connections between cesspools and surface well waters be 
traced? 778. What impurities do rain waters contain? 779. Ex- 
plain the workings of the Pasteur and Berkefeld water filters. 
780. Why must special attention be given to cleaning the water 
filter? 781. Explain the processes employed for the removal of 
mechanical impurities of water by sedimentation and the use of chem- 
icals. 782. Why should such purification be under the supervision 
of a chemist or bacteriologist? 783. What effect does freezing have 
upon the purity of water? 784. Why are precautions necessary in 
the use of ice for refrigeration? 785. What are mineral waters? 



348 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

786. How are artificial mineral waters prepared? 787. What are 
the more common materials used in their preparation? 788. Why 
should mineral waters be extensively used only by the advice of a 
physician? 789. What are some of the materials used for softening 
water? 790. Which are the least objectionable of these materials? 
791. Which are the most objectionable? 792. What can you say 
of the use of ammonia and ammonium carbonate for softening 
waters? 793. In washing clothing after contagious diseases, what 
materials may be used for disinfecting? 794. Why, in softening 
waters for household purposes, must caustic soda, potash, and bleach- 
ing powder be used with caution? 795. Why is it necessary to 
determine by trial the material most suitable for softening water? 
796. What advantage, from a pecuniary point of view, results from 
the improvement of the water supply of a community ? 



CHAPTER XX 

Food in its Relation to Household Sanitation and Storage 

797. What are the compounds usually determined in a food 
analysis? 798. Does such an analysis necessarily indicate the 
presence of injurious compounds? 799. W^hat are the sources of the 
injurious organic compounds in foods? 800. Why is it necessary 
to consider sanitary condition as well as chemical composition ? 
801. What are the sources of contamination of foods? 802. What 
is the object of the sanitary inspection of food? 803. How may 
flies carry germ diseases ? 804. Why should food be protected from 
impure air and dust particles ? 805. Why should places where vege- 
tables are stored be well ventilated? 806. How may the dirt ad- 
hering to vegetables be the carrier of germ diseases? 807. Why 
should the cellar in which food is stored be in a sanitary condition? 
808. What effect does the cleaning of streets and improvement of 
the sanitation of cities have upon the death rate? 809. Name the 
three natural disinfectants, and explain the action of each. 



REVIEW QUESTIONS 349 

810. Why must dishes and utensils in which foods are placed be 
thoroughly cleaned? 811. Explain the principle of refrigeration. 
812. What kind of ferment action may take place at a low tempera- 
ture? 813. Why is some ventilation necessary in refrigeration? 
814. What effect does refrigeration have upon the composition of 
food? 815. What relationship exists between unsanitary con- 
dition of soils about dwellings and contamination of the food? 
816. Why should special attention be given to the sanitary disposal 
of kitchen refuse? 817. Name the ways in which this can be ac- 
complished. 818. How may foods become contaminated through 
imperfect plumbing? 819. Mention the conditions necessary in 
order to keep foods sanitary. 



REFERENCES 

The following list of references is given for the use of the student 
in case additional information is desired upon some of the subjects 
discussed in this work. The list is not intended as a complete 
bibliography of the subject of foods. The advanced student will 
find extended references in the Experiment Station Record and the 
various chemical, physiological, and bacteriological journals. 

1. Snyder : The Chemistry of Plant and Animal Life. 

2. Minnesota Experiment Station Bulletin No. 54: Human Food 

Investigations. 

3. Cross and Bevans: Cellulose. 

4. Wiley: Principles and Practice of Agricultural Analysis, 

Vol. III. 

5. Minnesota Experiment Station Bulletin No. 74: Human Food 

Investigations. 

6. Parry : The Chemistry of Essential Oils, etc. 

7. U. S. Department of Agriculture, Farmers' Bulletin No. 142: 

Principles of Nutrition and Nutritive Value of Food. 

8. Mann: Chemistry of the Proteids. 

9. Minnesota Experiment Station Bulletin No. 85 : Wheat and 

Flour Investigations. 
ID. Armsby : Principles of Animal Nutrition. 

11. Sherman: Organic Analysis. 

12. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 43 : Digestion Experiments with Potatoes and 
Eggs. 

13. Unpublished results of author. 

14. U. S. Department of Agriculture, Bureau of Animal Industry 

Bulletin No. 49: Cold Curing of Cheese. 
350 



REFERENCES 35 1 

15. Wiley: Foods and Their Adulteration. 

16. Minnesota Experiment Station Bulletin No. 63 : Miscellaneous 

Analyses. 

17. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 

No. 13, Part 8: Canned Vegetables. 

18. Leach : Food Inspection and Analysis. 

19. U. S. Department of Agriculture, Farmers' Bulletin No. 256: 

Preparation of Vegetables for the Table. 

20. U. S. Department of Agriculture Year Book, 1905 : Fruit and 

its Uses as Food. 

21. Handbook of Experiment Station Work, 1893. 

22. U. S. Department of Agriculture, Division of Chemistry Bulletin 

No. 94 : Studies on Apples. 

23. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 

No. 69 : P>uits and Fruit Products. 

24. U. S. Department of Agriculture, Farmers' Bulletin No. 203 : 

Canned Fruits, Preserves, and Jellies. 

25. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 

No. 27 : Sugar Beet Industry. 

26. Sadtler : A Handbook of Industrial Organic Chemistry. 

27. Minnesota Experiment Station Bulletin No. 86: The Food 

Value of Sugar. The Digestive Action of Milk. 

28. Hutchison : Food and Principles of Dietetics. 

29. U. S. Department of Agriculture, Farmers' Bulletin No 93 : 

Sugar as Food. 

30. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 252 : Maple Sugar and Sirup. 

31. U. S. Department of Agriculture, Bureau of Chemistry Bul- 

letin No. 13, Part 6: Sugar, Molasses, Sirup, and Confec- 
tions. 

32. U. S. Department of Agriculture, Farmers' Bulletin No. 121 : 

Peas and Beans as Food. 

33. U. S. Department of Agriculture, Farmers' Bulletin No. 122: 

Nuts as Food. 
3-1- Maine Experiment Station Bulletin No. 54: Nuts as Food. 



352 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

35. California Experiment Station Bulletins Nos. 107 and 132: 

Investigations among Fruitarians. 

36. U. S. Department of Agriculture, Farmers' Bulletin No. 74 : 

Milk as Food. 

37. U. S. Department of Agriculture, Farmers' Bulletin No. 63 : 

Care of Milk on the Farm. 

38. U. S. Department of Agriculture, Farmers' Bulletin No. 149: 

Digestibility of Milk. 

39. Russell : Dairy Bacteriology. 

40. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 

No. 13, Part I : Dairy Products. 

41. U. S. Department of Agriculture, Farmers' Bulletin No. 131 : 

Household Tests for Detection of Oleomargarine and Reno- 
vated Butter. 

42. U. S. Department of Agriculture, Bureau of Animal Industry 

Bulletin No 61 : Relation of Bacteria to Flavor of Cheddar 
Cheese. 

43. Minnesota Experiment Station Bulletin No. 92 : The Digesti- 

bility and Nutritive Value of Cottage Cheese, etc. 

44. Lawes and Gilbert : Experiments with Animals. 

45. U. S. Department of Agriculture, Farmers' Bulletin No. 34: 

xMeats, Composition and Cooking. 

46. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 

No. 13, Part 7 : Lard and Lard Adulterants. 

47. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 193 : Cooking of Meats as Affecting Digestibility. 

48. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 141 : Experiments on Losses in Cooking Meats. 
See also Office of Experiment Stations Bulletin No. 102 : 
Losses in Cooking Meats. 

49. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 66 : Physiological Effect of Creatin and Creatinin. 

50. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 162 : The Influence of Cooking upon the Nutri- 
tive Value of Meats. 



REFERENCES 353 

51. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 

No. 13. Part 10: Preserved Meats. 

52. Richardson, W. D., Journal of the American Chemical Society, 

December, 1907: The Occurrence of Nitrates in Vegetable 
Foods, in Cured Meats, and Elsewhere. 

53. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 182 : Poultry as Food. 

54. U. S. Department of Agriculture, Farmers' Bulletin No. 85 : 

Fish as Food. 

55. U. S. Department of Agriculture, Farmers' Bulletin, Experiment 

Station Work : Digestibility of Fish and Poultry. 

56. U. S. Department of Agriculture, Farmers' Bulletin No. 249 : 

Cereal Breakfast Foods. 

57. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 

No. 50: Composition of Maize. 

58. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 305 : Gluten Flour and Similar Foods. 

59. Hammerston : Physiological Chemistry. 

60. Edgar : The Wheat Berry. 

61. Minnesota Experiment Station Bulletin No. 90: Composition 

and Value of Grains. 

62. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. loi : Bread and Bread Making. 

63. U. S. Department of Agriculture. Office of Experiment Stations 

Bulletin No. 156: Digestibility and Nutritive Value of Bread 
and Macaroni Flour. 

64. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 67 : Bread and Bread Making. 

65. University of Nebraska Bulletin No. 102 : The Effect of Bleach- 

ing upon the Quality of Wheat Flour. 

66. Snyder: Wheat Flour and Bread. 

67. U. S. Department of Agriculture, Office of Experiment Station? 

Bulletin No. 126: Bread and Bread Making. 

68. Lawes and Gilbert: Experiments on Some Points in the 

Composition of the Wheat Grain, of the Product in the Mill 
and Bread. 
2 A 



354 HUMAN FOODS AND THEIR NUTRITIVE VALUE 

69. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 

No. 13, Part 5 : Baking Powders. 

70. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 

No. 13, Part 2 : Spices and Condiments. 

71. Food Standards : U. S. Department of Agriculture. See Annual 

Reports of the Association of Official Agricultural Chemists. 

72. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 21 : Methods and Results of Investigations on 
the Chemistry and Economy of Foods. 
'j-}^. U. S. Department of Agriculture, Bureau of Chemistry Bulletin 
No. 13, Part 7 : Tea, Coffee, and Cocoa Preparations. 

74. The Respiration Calorimeter: Year-book U. S. Department of 

Agriculture, 1904. 

75. Year Book U. S. Department of Agriculture, 1902 : Cost of Food 

as Related to its Nutritive Value. 

76. See U. S. Department of Agriculture, Office of Experiment 

Stations Bulletins Nos. 82, 71, 129, 116, 37, 55, 150. See 
also other bulletins of the Office of Experiment Stations. 
']'] . Chittenden : Physiological Economy in Nutrition. 

78. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 98 : Effect cf Severe and Prolonged Muscular 
Work on Food Consumption. 

79. Henry : Feeds and Feeding. 

80. U. S. Department of Agriculture, Office of Experiment Stations : 

Dietary Studies in Chicago Bulletin No. 55. 

81. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 116: Dietary Studies in New York City. 

82. U. S. Department of Agriculture, Farmers' Bulletin No. 119: 

Banana Flour. 

83. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 159: Digest of Japanese Investigations on the 
Nutrition of Man. 

84. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 150: Dietary Studies at the Government Hospi- 
tal for the Insane, Washington, D.C. 



REFERENCES 355 

85. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 149: Studies on the Food of Maine Lumbermen. 

86. U. S. Department of Agriculture, Office of Experiment Stations 

Bulletin No. 143 : Studies on the Digestibility and Nutritive 
Value of Bread at the Maine Experiment Station. 

87. U. S. Department of Agriculture, Office of Experiment Stations, 

Experiment Station Work, Vol. Ill : Wells and Pure Water. 

88. U. S. Department of Agriculture, Farmers' Bulletin No. 88 : 

Pure Water on the Farm. 

89. Mineral Impurities in Water. See various bulletins of the Cali- 

fornia and New Mexico Agricultural Experiment Stations. 

90. Mason : Examination of Water. 

91. Department of the Interior, U. S. Geological Survey: The 

Quality of Surface Waters in Minnesota. 

92. FuERTES: Water and Public Health. 

93. U. S. Department of Agriculture, Farmers' Bulletin No. 124: 

Distilled Drinking Water. 

94. TuRNEAURE AND RussELL : Public Water Supplies. 

95. Vaughan AND Now: Ptomains and Leucomains. 

96. U. S. Department of Agriculture, Bureau of Entomology, 

Circular No. 71 : House Flies. 

97. Ellen H. Richards and S. Maria Elliott: The Chem- 

istry of Cooking and Cleaning. 

98. Dr. Woods Hutchinson, Saturday Evening Post, 1908 : 

The Real Angels of the House. 

99. Harrington : Practical Hygiene. 

100. Price : Handbook of Sanitation. 



INDEX 



Air, infection from impure, 287. 

pure, disinfectant, 290. 
Albuminoids, 23. 
Alkaloids, 24. 
Allspice, 202. 
Almonds, 77. 

Alum baking powder, 18S. 
Amids and Amines, 23. 
Animal and vegetable foods, economy 

of, 250. 
Animal foods, digestibility of, 220. 
Apparatus used in experiments, 301. 
Apples, 49. 

pectose from, 307. 
Ash, of foods, 4. 

elements of plants, 5. 
Asparagus, 43. 
Available energy, 217. 

nutrients, 216. 

Bacteria in food, 32. 

Baking powder, composition of, 186. 

cream of tartar, 187. 

phosphates, 189. 

alum, 189. 

inspection of, 191. 

fillers, 191. 

home-made, 191. 

testing for alum, 315. 

testing for ammonia, 316. 

testing for phosphoric acid, 316. 
Baking tests, 153-314. 
Barley preparations, 128. 
Beans, composition, 71. 

digestibility, 72. 

removal of skins, 72. 



strmg, 73. 

use of, in dietary, 74. 
Beef, 1 01. 

extracts, no. 
Beets, 41. 

Beverages, composition, 213. 
Bleaching of flour, 155. 
Bolting cloth, 138. 
Bread and bread making, 158-185, 

leavened and unleavened bread, 
158. 

chemical changes during making, 

159- 

losses during bread making, 160. 

production of carbon dioxide, 163. 

production of alcohol, 163. 

production of soluble carbohy- 
drates, 165. 

production of acids, 166. 

production of volatile compounds, 
167. 

production of volatile nitrogenous 
compounds, 172. 

wheat proteids, part taken by, 169. 

oxidation of fat, 173. 

starch, influence of, addition of, 173. 

composition of bread, 174. 

temperature of flour, 176. 

use of skim milk, 176. 

process of bread making, 177. 

digestibility of bread, 178. 

graham bread, use in the dietary, 
179. 

white and graham bread compared, 
180. 

mineral content of, 182. 



557 



;58 



INDEX 



new and old, 183. 

action of heat on, 184. 

different kinds of, 184. 
Breakfast foods, 1 21-13 2. 
Broth, 109. 
Butter, composition, 91. 

digestibility, 91. 

adulteration, 92. 

coloring, 92. 

renovated, 92. 

water in, 305. 
Buttermilk, 88. 

Cabbage, 41. 
Candies, 69. 
Canned meats, 118. 

vegetables, 46. 

peas, 75. 
Carbohydrates defined, 8. 
Carrots, 40. 
Cauliflower, 41. 

Cellars, storage of food in, 283. 
Cellulose and properties, 8. 
Cereals, 121-132. 

preparation of, 121. 

cost of, 121. 

value of, 131. 

use of, in dietary, 131. 

corn preparations, 122. 

oat preparations, 124. 

wheat preparations, 126. 

barley preparations, 128. 

rice preparations, 129. 

predigested, 130. 

phosphates in, 131. 

mineral matters of, 131. 

coffees, 210. 
Cesspools, 289. 
Cheese, 92-96. 

general composition, 92. 

digestibility, 93. 

use of, in dietary, 94. 

cottage, 95. 

different kinds of, 95. 

adulteration, 96. 



Chemical changes during cooking, 27- 

30- 
Chemicals, use of, in preparation of 

foods permitted, 36. 
Chestnuts, 76. 

Chicory, detection in coffee, 319. 
Chocolate, 212. 

adulteration of, 213. 
Cinnamon and cassia, 201. 
Cloves, 201. 

Coal tar dyes, testing for, 308. 
Cocoa, 210. 
Cocoanuts, 77. 
Coffee, composition of, 207. 

detection of chicory in, 319. 

glazing of, 208. 

substitutes, cereal, 210. 

types of, 209. 
Combustion of foods, 6. 
Cooking, changes during, 27. 

chemical, 27-30. 

physical, 30-32. 

bacteriological, 32. 
Corn, sweet, 41. 

preparations, 122. 
Cream, 87. 
Cream of tartar, 187. 
Crude fiber of foods, 9. 
Crude protein, 21. 
Cucumbers, 42. 

Dairy products, 80-97. 

use of, in dietary, 96. 
Dextrose, 64. 
Dietary standards, 245. 
Dietary studies, 244-260. 

object of, 244. 

mixed, desirable, 250. 

of families compared, 253. 

in public institutions, 259. 
Digestibility of foods, 214. 

of animal foods, 220. 

of vegetable foods, 222. 
Digestion, combination of foods, 223. 

factors influencing, 223. 



INDEX 



359 



amount of food, 224. 

method of preparation of food, 225. 

mechanical condition of foods, 226. 

psychological factors, 230. 

individuality, 229. 
Digestion and health, 219. 
Dishcloth, unclean, 292. 
Disinfectants, 281, 289, 295. 
Drying of foods, 2. 
Dry matter, 2. 

Egg plant, 44. 
Eggs, 1 1 4-1 1 8. 

composition, 114. 

digestibility, 116. 

cooking of, 116. 

use of, in dietary, 117. 
Elements in foods, 7. 
Energ}% available, 217. 
Energy value of rations, 246. 
Entire wheat, 145. 
Essential oils, 15. 

occurrence, 15. 

composition of, 16. 

food value, 16. 
Esthetic value of foods, 36. 

Fat, occurrence in food, 12. 
composition, 13. 
physical properties, 14. 
food value, 14. 
individual fats, 14. 
oxidation of, during bread making, 

173- 
Ferments, soluble, 34. 

insoluble, 34. 
Figs, 54. 
Fish, 113. 

Flavoring extracts, 56. 
Flavors, composition of, 48. 

occurrence of, 49. 

food value, 49. 
Flies, contamination of food by, 286, 
295- 



Foods, 215. 

digestibility of, 215. 

mechanical condition of, 226. 

palatability of, 228. 

physiological properties of, 228. 

ash of, 4. 

predigested, 130. 

sodium chloride in, 4. 

cost of, 231. 

market price and nutritive value, 
231-234. 

composition of, 234-263. 

comparative nutritive value, 231. 

economy of production, 250. 

habits, 250. 

notions, 252. 

relation to mental and physical 
vigor, 258. 

amount consumed, 262. 

injurious compounds in, 284. 

contamination of, 284, 292. 

sanitary inspection of, 286. 

storage in cellars, 288. 

infection from impure air, 287. 

utensils for storage, 291. 

raw, 27. 

cheap and expensive, 252. 
Fruits, composition of, 48. 

canned, 54. 

dried, 54. 

canned and adulterated, 55. 
Fruit extracts, 56. 
Fruit flavors, 55. 



Ginger, 200. 
Gliadin, 314. 
Gluten, addition of, to flour, 173. 

moist and dr\', 314. 
Gluten properties of flour, 151. 
Graham bread, 179. 

use in dietary, 180. 
Graham flour, 144. 
Grape fruit, 51. 
Grapes, 53. 



360 



INDEX 



Heat, action on foods, 30. 
Hickory nuts, 77. 
Honey, 68. 

Ice, 279. 

Inspection of food, 286. 

Inversion of sugar, 64. 

Kitchen refuse, 294. 
Koumiss, 88. 

Laboratory practice, 299. 
Lard, 106. 

substitutes, 107. 
Legumes, 71-76. 
Lemon extract, testing, 307. 
Lemons, 51. 

acidity of, 305. 
Lettuce, 42. 

Macaroni flour, 148. 

Mace, 202. 

Malted foods, 121. 

Maple sugar, 62. 

Meals, number of, per day, 248. 

Measuring, directions for, 302. 

Meat broth, 109. 

Meats, 98-120. 

general composition, 98. 

proteids of, 99. 

fat of, 100. 

water of, 98. 

texture of, 107. 

cooking of, influence of, on com- 
position, 108. 

extractive materials, no. 

smoked, in. 

boric acid in, 312. 

saltpeter in, in. 

canned, 118. 
Melons, 43. 

Microscope, use of, 304. 
Milk, importance in dietary, 80. 

general composition, 80. 

souring of, 86. 

condensed, 87. 



digestibility, 81. 

sanitary condition, 82. 

certified milk, 84. 

pasteurized, 84. 

color of, 85. 

preservatives in, 86. 

goat's, 88. 

human, 89. 

adulteration of, 89. 

prepared, 88. 

formaldehyde in, 310. 
Mineral matter, 4. 

in ration, 5. 
Mineral waters, 279. 
Miscellaneous compounds, 16. 
Mixed nitrogenous compounds, 25. 
Mixed non-nitrogenous compounds, 

16.. 
Moisture content of foods, variations 

in, I. 
Moisture in foods, how determined, 2. 
Molasses, 65. 
Mustard, 199. 

testing for turmeric, 318. 
Mutton, 103. 

Nitrates in foods, 45. 
Nitrites in foods, in. 
Nitrogen free extract, 1 1 . 

defined, n. 

composition, 12. 

how determined, 12. 

variable character of, 12. 
Nitrogenous compounds, 17. 

general composition, 17. 
Non-nitrogenous compounds, classi- 
fication of, 7. 
Nutmeg, 202. 
Nutrients, available, 216. 
Nutritive value of nitrogenous com- 
pounds, 16. 

starch, 9. 

sugar, n. 

nitrogen free extiact, n. 

fat, 12. 



INDEX 



361 



protein, 19. 
amids, 2;^. 
Nuts, 76-79. 

use of, in dietary, 



78. 



Oat preparations, 124. 
Oleomargarine, 92. 

detecting, 310. 
Olive oil, testing, 308. 
Olives, 54. 
Onions, 42. 
Oranges, 50. 
Organic acids, 15. 

occurrence in foods, 15. 

influence on digestion, 15. 

use in plant economy, 15. 

production during germination, 15. 
Organic compounds, classification of, 

7- 
Organic matter, 6. 
Oysters, 114. 

Palatability of food, 228. 
Parsnips, 40. 
Peaches, 53. 
Peanuts, 76. 

fat from, 309. 
Peas, 74. 

canned, 75. 
Pectose substances, 11. 
Pepper, 198. 

Phosphate baking powders, 189. 
Physical changes during cooking, 30. 
Physiological properties of foods, 228. 
Pistachio, 77. 
Plumbing, sanitary, 297. 
Plums, 53. 
Pork, 104. 
Potatoes, 37. 

composition, 39. 

digestibility, t,S. 

nutritive value, 38. 

sweet, 39. 
Poultrj', 112. 
Predigested foods, 130. 
Protein, composition of, 19. 



properties of, 19. 

combinations of, 20. 

types of, 20. 

crude, 21. 

food value of, 22. 

amount of, in ration, 246. 
Psychological factors in digestion, 230. 
Pumpkins, 45. 

Rational feeding of man, 261-267. 
Rations, wide and narrow, 245. 

standard, 261. 

object of, 261. 

examples of, 264. 

requisites of, 266. 

protein requirements of, 246. 

energy value of, 246. 
References, 350. 
Refrigeration, 292. 
Refuse, disposal of, 294. 
Renovated butter, 92. 
Review questions, 323. 
Rice preparations, 129. 

Saccharine, 70. 

Saltpeter in meats, iii. 

Sanitary condition of vegetables, 45. 

Sanitary inspection of food, 286. 

Sausage, iii. 

Sodium chloride in foods, 5. 

Soil, sanitary condition of, 294. 

Spices, 212. 

Spinach, 42. 

Squash, 45. 

Starch, 9. 

occurrence, 9. 

composition, 9. 

properties, 10. 

food value, 10. 

influence of heat on, 10. 
Strawberries, 52. 
Sugar, defined, 11. 

beet, 58. 

cane, 58. 

commercial grades, 58. 

manufacture of, 59. 



l62 



INDEX 



sulphur in, 50. 

digestibility of, 59. 

value of, in dietary, 61. 

adulteration of, 63. 

maple, 62. 

dextrose, 64. 
Sunlight as a disinfectant, 290. 
Sweet potatoes, 39. 
Syrups, 66. 

sorghum, 66. 

Tea, 203-206. 

black, 203. 

green, 204. 

composition of, 214. 

judging of, 205. 

adulteration of, 206. 

physiological properties of 206. 

examination of leaves, 318. 
Toast, 184. 
Tomatoes, 43. 

Underfed families, 251. 

Vanilla extract, testing, 307. 
Veal, 102. 

Vegetable foods, 222, 
Vegetables, 37-47- 

edible portion, 47. 

canned, 46. 

sanitary condition of, 45. 

digestibility of, 222. 
Vinegar, 193-197- 

preparation of, 193. 

different kinds of, 195. 

adulteration of, 196. 

solids, 316. 

specific gravity, 317. 

acidity, 317. 
Volatile matter, 6. 

Water, drinking, 268-283. 
importance, 268. 
impurities in, 269. 
mineral impurities, 270. 
organic impurities, 271. 
purification of, 272-278. 



analysis, 271. 

and typhoid fever, 273. 

improvement of, 276. 

boiling of, 276. 

filtration of, 277. 

distillation of, 278. 

materials for softening water, 280, 

testing purity of, 320. 
Water in foods, i. 

how determined, i. 
Water supply, economic value, 282. 
Waters, mineral, 279. 
Weighing, directions for, 302. 
Wheat cereal preparations, 126. 
Wheat flour, 133. 

spring and winter wheat flour, 133. 

starchy and glutenous, 135. 

composition of, 136. 

process of milling, 136-140. 

patent, 142. 

grades of, 142. 

composition of, 143. 

ash content, 145. 

graham, 145. 

entire wheat, 145. 

by-products, 146. 

aging and curing, 147. 

macaroni, 148. 

color, 148. 

granulation, 149. 

capacity to absorb water, 150. 

gluten, properties of, 151. 

unsoundness of, 152. 

baking tests, 153. 

bleaching of, 155. 

adulteration of, 156. 

nutritive value of, 157. 

water in, 304. 

ash in, 305. 

acidity of, 313. 

moist and dry gluten, 314. 

Yeast, action of, 161. 
compressed, 162. 
dry, 163. 



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